I think that most people who have many years of boating under their belts will admit to dropping their boat in with no drainplug at least once...
Mine was at the Wolfeboro town docks on a busy Saturday afternoon. My friend backed me down, I slid off and started to back up while he took off with the truck and trailer. I immediately realized that I was going down and started screaming for him to come back. Luckily someone flagged him down and I made full throttle trailering manuever that I am still surprised to this day did not end me up in the back of the truck!