A counselor is standing alone on stage looking at his/her watch, when finally a camper comes along.
The counselor asks where he/she has been, and the camper replies, “Throwing pebbles in the lake.”
This occurs a few more times as more campers come along and say that they, too, were “Throwing pebbles in the lake.”
A soaking wet camper eventually comes by in completely drenched clothes. The counselor asks, “Who are you?”