Oddly enough, I went to a private Mennonite High School. I'm not even Mennonite, but Mom thought it would be a good idea. I have tons of Menno friends from that experience. To answer your question: it depends. If they're strict Menno's, they frown on that shit, if they're more relaxed, they join in.
Even relaxed Menno's are funny, they'll go party on Friday and Saturday nights, then beg for forgiveness on Sunday. Saw it all the time in HS.