The phrase rawr XD comes from early internet chat culture, where rawr was jokingly translated as a declaration of love in dinosaur and XD stood for a laughing, eyes closed face. This clip is credited as a sound of Frank the Combine, giving the familiar phrase a short voiced punchline that can be shared out of context. It spread through meme edits, chats and soundboards because it instantly signals a very specific tone, playful, nerdy and intentionally awkward, without needing any setup or explanation from the creator using it.