Fish found this video of a pretty funny prank.  Well, I guess the "pretty funny" part is kinda objective.  It's pretty funny to watch this happen to someone else, but it is definitely not funny if it happened to you.  Especially if there are old nails or other random crap beneath the floor.

So, if you want to make your Dad mad, but have some random people on the internet think you are hilarious, push your father through the hole in the floor that he just made when he was putting new flooring in.