British Disco is a powerful dance that kills anyone who sees it. Johnny Toast is a master of this, he himself being British. Other British people cannot be affected by this dance. The Undead are also unharmed as they are already dead.
Not much is known about its origins. It was implied Johnny Toast accidentally killed his wife with British Disco.
The British Disco is not 100% lethal, as a man named Johnny Bravo survived the dance. However upon witnessing it, his eyeballs left his skull, called him a rip off artist and punched him in the face (otherwise resulting in blindness.)
If used to its full potential though, the dance can create a nuclear explosion that would wipe out anyone within the vicinity.