Literally "Read The F**king Manual"; a term showing the frustration of being bothered with questions so trivial that the asker could have quickly figured out the answer on their own with minimal effort, usually by reading readily-available documents. People who say "RTFM!" might be considered rude, but the true rude ones are the annoying people who take absolutely no self-responibility and expect to have all the answers handed to them personally.
"Damn, that's the twelveth time that somebody posted this question to the messageboard today! RTFM, already!"
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