fortunately i have never had to wait around to get rescued, but on a normal caving trip needing time killing, there is always singing ("show me the way to go home" if the leader cant find the way on, or Monty Python type filth if just bored), snogging, sleeping, finding the smallest, darkest lair i can fit into and turning my light off and waiting for unsupecting cavers, getting shouted at for wandering off exploring, mud fighting, making rabbit droppings out of mud, there's the water slide down Fechan to play on, tying other cavers to convenient bits of rock or each other, water fights, splashing around, looking for formations that look rude....
lots of stuff