My own 18-year celebration (when else? :P ), three and a half years ago. I remember waking up at 4 am the next day (I always wake up ungodly early after drinking), walked up into the living room, and it was COMPLETELY trashed. First I walked to a nearby 24h petrol station to buy a Coke, then I got home and spent the next 9 hours righting bookshelves, washing every surface in the room (both fabric and hard ones), performing an exorcism in the kitchen.. you know, the usual drill when a party got way out of hand, and your parents return at 4 pm :P
Learned my lesson, though.