Dance Party. Bring out a boom box or speaker and get piggy with it while on the tramp. My girls love to do this with all their girl friends. Add costumes for even a more fun flare.
Twister. Using 4 different colors of chalk, draw several circles on the tramp. Call out different positions using your hands and feet. Everyone will be laughing.
Helicopter. We used to play this on the playground as kids using a jump rope. I’ve played it on the tramp with my kids and they loved it. Using some kind of rope (folded in half), swing over your head saying “helicopter, helicopter please come down.” Another person says, “not until you guess my favorite color, food, sport etc.” Whom ever has the rope then unfolds it and those with the right answer jump over the rope as it is swung around the tramp.