Team Fortress 2 is Valve's class based multiplayer shooter first released in 2007, and the Medic is its German doctor class known for healing teammates with his Medi Gun. His loud, theatrical voice lines have been clipped for soundboards for years, shared in gaming chats, videos and meme edits. This tank callout comes from that tradition of short in game warnings turned into reactions. It stays popular because players instantly recognise the character, and the warning works outside the game whenever a big threat appears on screen.