As a person who chooses not to drink, I am beginning to think I'm going to be a minority in d-school.
One of the dentists I work with who went to NYU said she partied hardcore through most of it. It wasn't until she realized she wanted to do an endo residency and that grades mattered that she stopped partying. She never got into an endo residency because she couldn't compensate for years of slacking off.
A dentist I shadowed who went to NJDS said they had parties with the med students every weekend, and the faculty would go too. He survived his four years despite heavy partying, but he only needed to pass because he didn't want to specialize. (He graduated in the '80s, btw.)
It's entirely possible to have fun without drinking. Just sayin'. Some things are more important, like my future and not risking screwing it up. Gonna get flamed for my disagreement with the majority I bet.