I learned this expression (which stands for "Fuck Off And Die") through the occasionally sullen Larry Mullen, Jr., U2's drummer. It is his favorite saying, according to the book U2 At The End Of The World, by Bill Flanagan.

During a staged protest of the Sellafield Nuclear Power Plant in England, U2 were playing with the Semaphore flags, like the ones the Beatles used on the cover of their 'Help' album. The idea was to videotape them moving from HELP to FOAD. Unfortunately, by that time, sleep deprivation and radiation suits that made them look like clones of the Michelin Man had taken their toll and the event turned into a swordfight with the flags between the members.

Source: U2 At The End Of The World, by Bill Flanagan.