"Flushed"

My 14 month old has learned a new trick that he finds hysterical,me....not so much.
When he sees me heading to the "ladies room" he runs at top speed to make it in before I shut the door,now if I do shut it he stands at the door screeching so I always let him in.
Well,that was no big deal till yesterday.
As soon as he sees me uhhhhmmmm sit down,he flushes the toilet and runs out laughing!!!!!!!!!!!!!!!!!
This is not a pleasant experience for me but it seems that it's one of the highlights of his day.
Oh the endless joys of mommy-hood.