5.

Rhythmic gymnastics: if your hoop gets stuck in the ceiling, you have to keep going.

The rules for rhythmic gymnastics state that if any of the apparatus used in the routine — this year the hoop, the ball, the clubs, and the ribbon — breaks or "gets caught in the small beams of the ceiling," the gymnast doesn't get to start over. She won't be penalized for the breakage or ceiling-sticking, "but will only be penalized for the consequences" — which, given that much of rhythmic gymnastics is about correctly manipulating the apparatus, could be severe. Rhythmic gymnasts can also get deductions if their ribbon ties in a knot, or if their hoop vibrates in midair.