Team Fortress 2 is a team based shooter released by Valve in 2007, and Pyro is one of its nine playable classes. The character wears a full gas mask and fireproof suit, so all of his voice lines are deliberately muffled and hard to understand, which became one of his defining traits. Short clips of Pyro vocalisations have circulated for years on forums, videos and soundboards, where fans use them out of context for comedy. This boo clip survives because it captures that joke in just over a second.