Some fans think it's a good idea to run alongside the bikes in the Tour de France. Other fans think these people should be punched in the face.
One spectator at this year's race took matters into his own hands, as he wiped out one of these 'bike chasers' with an impressively timed right hook.
Keep a close eye on the right of the picture, and in particular the guy in white running - for some unknown reason - alongside the rider wearing green.
The hit he received was so fast and accurate it put him straight to the ground, but rather fortunately the riders in close proximity managed to avoid a multi-bike pile-up.
This may act as a deterrent to anyone else who thinks they can match the pace of elite athletes on bikes.