OK, I had my fun with some of you here, but I also had fun with my kids. Now this is a fun little joke that doesn't have to wait til the next April Fools day, go out and try it now. All you need is some of that clear plastic carpet cover with the little spikey rubber things that dig into the carpet. The trick is simple, turn it upside down and wait for someone to walk across it. Laughs guaranteed.