WASHINGTON, United States (AFP)—Donald Trump celebrates his 80th birthday in typically forceful style on Sunday, as the oldest US president ever to take office holds a bloody cage match on the White House lawn. The unprecedented "UFC Freedom 250" event will see 14 Ultimate Fighting Championship stars beat each other to a pulp in a giant arena called The Claw. Costing $60 million, it's linked to this year's festivities for the 250th anniversary of US independence -- but it also happens to fall on the day that Trump enters his ninth decade.