Wikipedia: The high five is a celebratory hand gesture that occurs when two people simultaneously raise one hand, about head high, and push, slide or slap the flat of their palm and hand against the palm and flat hand of their partner. The originator of the high five is a subject of controversy. :)
Three tomatoes are walking down the street -- a pappa tomato, a mamma tomato, and a little baby tomato. Baby tomato starts lagging behind. Pappa tomato gets angry, goes over to the baby tomato, and squishes him... and says, catch up! :)