The phrase comes from everyday Russian slang, where khz is shorthand for kto znaet, who knows, and zachem eto means why is this needed. The exact original recording and speaker are unknown, and the clip circulates mainly as a short reaction sound shared between chats, edits and soundboards. Its appeal is how ordinary it sounds, like a friend commenting in real time rather than an actor performing a line. That everyday tone has kept it useful for reacting to anything random, pointless or hard to explain online.