There is no confirmed source for this clip; it appears to be a user-uploaded vocal gag rather than audio taken from a film, show or game. Sounds like this live a second life on soundboards, where short mouth-made effects are collected for streamers, editors and meme pages. The 'pew pew' laser is one of the internet's oldest joke weapons, showing up in everything from home videos to gaming streams whenever someone wants a battle to feel deliberately unserious. Its charm is its handmade quality: anyone can do it, so everyone does.