What about everybody's favorite summer toy - the Dive Stick. It was a plastic stick that sank to the bottom of the pool. It would stand up becasue the bottom of the stick was weighted.

You then raced your friends to the to collect as many as possible...problem was some kids raced ass first and well...found their own bottoms had a little added weight.

In 1999 (i think) Wal-Mart recalled more than 9 million of the buggers.