premise: Three men in green outfits watch as a fourth man breakdances in front of a crowd and a tour bus parked on the street. hypothesis: Three men in green outfits set down mats to start breakdancing while a forth man sits by and waits his turn to perform for the crowd.
contradiction: The three men who watch can not also set down mats.  The fourth man who sits by and waits, can not be the fourth man who breakdances.