The phrase czemu to czynisz is Polish and uses a slightly old fashioned construction, which gives this short clip a solemn, almost biblical weight compared with everyday speech. That contrast is why it circulates as a reaction sound rather than a plain question, shared in edits, chats and soundboards when words fail. Because the exact recording source is not widely documented, its life online is defined by reuse: creators borrow the line whenever a scene needs instant disbelief, disappointment or mock horror at what someone has just done.