<p>I usually mix it up between Cal and Berkeley, but if I had to pick one I’d say Cal (mostly because that’s what I’m used to calling it). I don’t think it’s ambiguous. No other school calls themselves Cal … it’s UC Berkeley’s nickname. To me, Berkeley is a city. Also, it’s not the only college in Berkeley so it doesn’t uniquely identify it. </p>
<p>“Where are you going to school?”
“Berkeley.”
“Berkeley City College?”
“No. Cal.”
“Ohhh, got it.”</p>