fuck off

1.  Go away, get out of here, as in Fuck off or I'll call the police. This idiom is used only as a command. [Vulgar slang; 1920s]
2.  Spend time idly, loaf or shirk one's duty. For example, After twelve years of school some kids feel they're entitled to fuck off, or You're always fucking off instead of working. [Vulgar slang; 1940s]
3.  be fucked off. To be furious, as in They didn't show up, and I am really fucked off. [Vulgar slang; c. 1940] Also see piss off.

The verb has 3 meanings:

Meaning #1: be lazy or idle
  Synonyms: bum around, bum about, arse around, arse about, loaf, frig around, waste one's time, lounge around, loll, loll around, lounge about

Meaning #2: leave immediately; used usually in the imperative form
  Synonyms: scram, buzz off, get, bugger off

Meaning #3: get sexual gratification through self-stimulation
  Synonyms: masturbate, wank, she-bop, jack off, jerk off