The phrase comes from everyday German slang, mixing the shortened 'bish' for 'bist' with 'behindert' used here as a crude insult rather than a literal description. Clips built around short shouted lines like this spread through soundboards and short form video because they need no setup and can be reused in many situations. This short version became popular as a shareable reaction, passed around for prank edits and chat replies where a harsh, funny put down is the whole joke.