Fill a cooler with cheese, cured meats, beer or wine, and stash it in the woods somewhere along the route of the next day's ride. When the group reaches that spot, feign a mechanical, then unveil your surprise.
Ride Cape May, New Jersey, during the migration of the Monarch butterflies in late August or early September—one of the half-million winged wonders will alight on your shoulder now and then.
Fade casually to the back of the group. At a slow-speed section, unclip one foot then drag your cleat on the pavement—it sounds exactly like a bike crash.