"Winnebago Surfing" joke

The wonderfully dangerous sport of WINNEBAGO SURFING was invented
by rock climbers in a national park in Western U.S. The surfer
lurks in an overhanging tree, rock, output port of tunnel, etc.,
and hops a ride on the top of a slow-moving motorhome driven by a
tourist. He waves at passing motorists, jumps up and down noisily
on the roof, or hangs upside-down over the windshield and makes
faces at the driver (while anchored securely with climbing
equipment, since the mark invariably hits the brakes)! Ideally,
the surfer catches another tree or pre-rigged rope and disappears
vertically before the mark can dismount to investigate
(camouflage clothing is useful here). An informant in the
National Park Service says that the Department of the Interior
ordered the NPS to deal harshly with Winnebago Surfers, and to
suppress all mention of Winnebago Surfing in internal newsletters
and publications, lest the practice become widespread.