Hæ tuller du is an everyday Norwegian expression of disbelief, roughly are you joking, and this clip is credited to DreamyMorten on user soundboards. Short reaction phrases like this spread because they are easy to recognise, loop and drop into unrelated videos, even for viewers who do not speak the language. The clip stays in use as a compact meme reaction for streams, edits and group chats, where a baffled response in another language feels funnier and more expressive than a plain English equivalent.