It's more fun to watch if you don't know what's coming, but here goes:
At George Burns' 100th Birthday Concert in Las Vegas, he is attacked by a machine-gun toting vigilante who thinks 100 years is long enough. Enraged but unhurt, America's favorite old geezer grows into a giant Godzilla-like behemoth and rampages through Las Vegas, wreaking havoc and battling other legendary show business giants.