When I crossed a bunch of alumni came down for ritual and the ensuing party. It's always interesting to see what the house had been before you joined. So then they schooled us in some drinking games from back in the day.
This was my first real alumni experience and I was impressed at the immediate bond that springs up between alums and newbees. College must've been a magical time for these guys, and they're always invited to relive them. Fraternities (and sororities for that matter) really are for life.