Captain Kirk fought the alien Gorn in the Star Trek episode "Arena" in 1967. It was a lame fight, often called the lamest fight ever. And the lamest move was Kirk's two-handed punch in the Gorn's back that barely registered. But then the move was used again and again in other episodes. It was still lame, but it became part of the Star Trek landscape.
Maybe the move looked cool in 1967, when the episode first aired. After all, the airwaves at the time were filled with homelier fare like The Andy Griffith Show and Bonanza. The punch continued to make appearances in later Star Trek entries: It's featured in the 1980s TV series The Next Generation, and throughout the 90s in Deep Space Nine. Its resilience has led to a ton of speculation among fans: Is the punch somehow an official element of Star Trek's mythos? It doesn't look threatening at all, so there must be some other reason that explains why it's so prominent.
I can assure you it did not look cool even in 1967. It made my dad laugh. We were just glad to have a space show on TV. The double-handed punch didn't originate with Star Trek, but it survives because of Star Trek. Jordan Pearson talked to a Star Trek stunt coordinator about the history the move and why the show continued to use it so much that we think of it as an iconic part of Star Trek. -via Metafilter