OP, you might recount that story about the parent calling the sheriff, and then say, “While we wouldn’t do that, are you sure that there won’t be anybody at this party with parents like that?”
If he’s going to college next year, you might also point out to him that underage drinkers at college rarely get arrested by the real police, but that high school students often do.
At an apartment complex it won’t be a parent calling it will be the neighbors.
While I think you could say no to it, that you aren’t comfortable with it, since he is obviously still living at home, dependent on you, etc, I personally would lean away from using that right unless you absolutely feel like he is in danger by going.
So what would I recommend? What others have mentioned
1)I would point out that since there is an older person at the party, there likely will be alcohol and or drugs (to be honest, these days that is true at a lot of parties with teenagers, as it was in my day), and talk about the consequences if the party does get busted up by cops, that there could be consequences to him (depending on the laws in the area) if he gets caught underage drinking or using drugs. That would be treating him like an adult, giving him the consequences in a rational way, how it can affect him (please don’t do what one parent who asked me for advice and did the opposite did, they gave the kid the whole thing about drinking leading to alcoholism, if he tries drugs he will slide down the slippery slope, they whole morality thing, the kid of course ignored it, and ended up doing something stupid). Lot more effective to say getting busted for underage drinking would lead to loss of driving privileges, possible loss of college admission, possibly consequences with car insurance when he is able to drive again. Don’t be afraid to use personal examples if you want from when you grew up, I never gave my son the idea that we grew up in a perfect world or were perfect ourselves and I told him the consequences I saw.
2)I second 1000% that if he drinks or does drugs, or simply feels too tired at the end of the party to drive, to either call a cab or call you or another family member for a ride home, no questions asked. A lot of parents say that, but then when they get called at 2am to pick the kid up, immediately read them the riot act. Among other things, if this is a typical party the kid is gonna be exhausted by the end of it, and I can’t emphasize how many accidents I saw caused by fatigued drivers, and if there is drinking involved, the combination of fatigue and even a low BAC can be deadly (I was on a rescue squad at one point, saw more than a few of these), so tell him if he is tired, call or grab a cab or something (a ride home with another kid can be just as problematic). Not foolproof, of course, lot of times people who are not fit to drive feel they are, but having a reliable alternate may make them more likely to use it if they know it will be without judgement. I never understood parents who pull the judgement route (and sadly seen a lot of that), when they themselves did stupid things, it is much like “Back to the Future” when the kid sees what his mom was really like:)
I have been a “you can call me at any time” parent since my children started being independent, and it has been a positive thing. It helps, I’m sure, that I’m sincere.
It is very easy to get hauled in for underage drinking.
Cop shows up at door because neighbor complained about loud music.
Scenario one: Someone answers door, steps outside and closes door. Assures officer the music is turned down.
Scenario two: Door is left open while someone talks to cop and he sees liquor and empty beer bottles. Busted.
It’s his future.
You can pull rank and tell him no but now that he is about to be 18 that strategy is going to run its course soon. So, you play it smart. You lay it out for him how some kids think its really cool to get puke faced drunk and stoned and put all kinds of stuff into their blood streams and have sex with and without protection and then get to raise kids they didn’t plan for or acquire very exotic STD’s as a reward. That sounds lovely. Right around then he might interrupt you to say none of his friends do any of that. Tell him in whatever style works for you to zip it until you are done.
You continue. Here is what happens to people who get a criminal record for DUI or who kill someone while DUI or destroy property while DUI. He will get to spend the rest of his life dealing with court hearings and lawyers and supporting someone who claims they have a neck injury real or not. That sounds spectacular.
All because they wanted a beer or two.
Or, all because heroin sounds fantastic.
Then you tell him in no uncertain terms you will not be bailing him out of any if the above happens. You think he should get used to jail for a few weeks until you get around to it.
Or, simply tell him there are some things you can’t fix. If he kills someone in a DUI event you can’t make the other party come back alive again.
All because beer tastes so good. All because hooking up is so much fun. Well, don’t bring up that last point because hooking up might not always be a bad thing but bring up the rest of it.
He will tell you his friends don’t do that. Disagree with him. I like all my kids friends. But I do not trust many of them at all. My advice might sound harsh but both of my kids saw the sense in my message and don’t really like idiots who do those kinds of things. Both of my kids want a big house, a nice relationship and healthy bodies and all the things mentioned above are the opposite of that. That is the line of attack I would use. Cold hard logic. STD’s are not cute. At all, Keep it zipped up. DUI lasts forever. Don’t even think about it and the idea of drinking and partying without doing any of this is fantasy not reality.
^^ITA plus (I have a boy and a girl) you don’t want your son to be so out of it he can’t remember if a girl gave consent or not. Too much booze/drugs just opens them up to all kinds of unintended behavior.
Then there’s the Jeff Foxworthy bit about the best parties:
“Hey Officer Mitchell ! I thought you didn’t want to come back here tonight!”
Has he not already visited this friend at his apartment? Is the concern that it’s being called a party? I would imagine you have probably had the drinking/consent discussion with him prior to this, right?
I think parents “like that” are heroes. They may have saved someone’s life by breaking up that party before someone got sexually assaulted or got behind the wheel.
If he were my son, I’d say of course he can go provided his father and I are invited too. After all, if it wasn’t for us, he wouldn’t even be here 
Was calling the Sheriff the only way to do that? Or even the best?
True stories.
DS was invited to a party at a friend’s house. I knew the family very well…wonderful people…BUT my son was NOT invited by the folks at the house. He was an 18 year old HS senior. I called the family and inquired. The mom was happy I called…said she couldn’t believe others had NOT called. Turns out, they had divided up the inviting duties amongst several friends. No problem…parents were going to be there…son went.
DD after her 18th BD was invited to a party. I didn’t know,the people at all. I asked for a phone number so I could call them. DD pitched a fit. Said it was not necessarily…and that I didn’t trust her. Tough. I asked for a number…again…and got one. I called, and the dad answered the phone. I asked “will there be adults in the house to,supervise during this party?” His answer…" I don’t know."
DD did not go to that party. There was a bit of door slamming and the like…but you know…at the end of the day, I was responsible for making this decision.
Later in the evening…DD apologized and said she understood my stance.
I know that your son will be in college come fall…and will attend parties in apartments with older kids.BUT…if you aren’t comfortable with this arrangement now…just say no.
You won’t be the first parent to do the same.
Also @SouthernHope , it’s entirely possible that no shenanigans are planned - or will happen. Not every party/group of kids is looking to go off base. Ok to let your son know that you are not assuming they will, BUT to consider it an early 18th b-day present to educate him of what changes do occur after 18!!!
My youngest son is turning 18 this weekend…still in HS, but I think this is definitely the “no man’s land” of parenting. I’d have the talk with him, etc., let him go (depending on his driving situation, make a judgment about driving or not – my son is a good, responsible driver and I trust him not to drink and drive), but H would spend the evening chilling in his car, discretely, at the corner near the apartment complex. No one flame me…he would do that (maybe I would think it was a bit much) but I’d relax at home a little easier that night. Once they’re in college, they’re not driving and the police are not intervening, usually, with students on campus. High school is really much more difficult.
I like all the advice here. Our job is to teach our kids how to protect themselves, while protecting them from themselves till they can understand the lesson. You know what stage your own son is at in the process best of anyone.
I didn’t learn till much later I had an idling at the corner father.
I would also tell other parents, proactively, that you have heard about this secret party and you do not support or condone it. I would even call some of them, and ask them what they are hearing. They may be thinking they don’t want to be the brakes when it isn’t their occasion. Why not share the parental load?
As mentioned, the 20 yr old is underage in my state, and the legal ramifications of furnishing alcohol are real and serious. 18 isn’t magic. I would have told mine " we are totally uncomfortable with the situations that may develop, and are asking you to put a stop to this idea". Go ahead and be disapproving. Better have him mad than dead. (I appreciate the “be safe!” And “call us if you’re drunk” but realistically, a drunk kid drives drunk. A high kid makes bad decisions. And so forth)
Remember, he hasn’t told tou about it. Doesn’t that set off an alarm in your head? Probably not planning to watch tv and play cards…
Just an FYI…if the police are called…and there is alcohol, in my state EVERYONE underage would be charged whether they had a drink in their hands…or not.
My kids asked me that question and changed plans based on my answer.
Well their question was about illegal drugs. I emphasized they had an attorney friends card in their wallets. That really got their attention, in a good way.
You could try
“You may be an adult but you still live in our house, be home by midnight!” plus all the necessary warnings concerning dui, stds, drugs, intoxication, etc. . .
Here is a thought…could you offer to host this party at YOUR house? You could even sweeten the deal by offering to order out pizza, and provide beverages.
Maybe make that offer…