The phrase is everyday Dutch slang, with klootzak being a common strong insult roughly equivalent to jerk or asshole in English. Short foreign language insults like this spread easily on soundboards because the emotion carries even when the words need translating, and the clip is brief enough to drop into chats, streams and edits without context. It has settled into use as a reaction rather than a quote from a known scene, shared mainly for arguments, callouts and playful fights among friends who want a harsher punchline than English offers.