The story
Probably from Superman, a comic-book superhero with superhuman strength and speed.
Etymology from Wiktionary, CC BY-SA 4.0.
superman punch
Today it means: A technique used in Muay Thai, Sanshou, kickboxing, ITF-style taekwondo and mixed martial arts, which involves bringing the rear leg forward to feign a kick, then snapping the leg back while throwing a cross, resulting in greater power behind the punch. Full definition →