Each summer in St Louis Hostelling International holds a fundraiser "Moonlight Ramble" ride. It used to start at 2:00 AM after the bars closed but in recent years the start time has been moved up to midnight. The first year that I rode it had 25,000 participants. It was wall-to-wall drunks and assorted other people who only bicycle one night a year. I nearly T-boned a guy who, without any warning, made a sudden left turn right in front of me so that he could look back for his girl friend.
I've done it a couple of times since but it's not enough fun to warrant staying up past my bed time.