PTFS is short for Pilot Training Flight Simulator, a long running Roblox flight simulator where players train, fly routes and roleplay airport jobs. Its community shares short in game clips outside the game, and this walrus call became one of those portable sounds, passed around on soundboards and in Discord chats. Like the Roblox oof, it works because everyone recognises it instantly even without video. It survives as a reaction noise rather than a gameplay cue, used whenever a chat needs a random, deadpan interruption.