Try eating fruit, nuts, or a protein bar - something that has nutritional value.
Dark chocolate is good for you… but not in excess, of course. 
I personally love Justin’s Dark Chocolate Peanut Butter Cups. I always feel more sharp/focused after eating them for some strange reason, but that might just be my imagination. I personally do not feel more energized after eating junk food, but if that method has worked for you and/or your friend go ahead. Just know your limits. Consuming caffeine is the best way to be energized.