The clip comes from the world of Postal, the long running video game series by Running With Scissors known for violent satire and its antihero the Postal Dude. Postal has built a cult following since the late 1990s for pushing jokes about American culture, weapons and everyday frustration to an extreme. This Second Amendment line fits that style perfectly, so it spread on soundboards and in meme edits detached from any single scene. It remains popular because the phrasing is instantly recognisable to US audiences.