I practically grew up on my family's trampoline. Me and my friends would flee to it for shelter from the EVIL ROOSTERs, hold little olympics, perform DBZ moves, and just lay and talk on it.

The most time-honored trampoline game was either called Trip the Dip or Chip the Dip. I can't remember which one. But you have one person be the dip and they roll around flat on the trampoline while everyone else cowers on Base (which was a swingset conveniently placed next to the trampoline) and when they got off base, the dip would try and catch them.

This game has been revitalized as "Carpet Worm" for indoor use. The carpet worm rolls around on a carpet and if they catch someone, then that person is the new carpet worm.