Is it ensure, insure, or assure?
: ''RTFM'' for ''Read the Fucking Manual,'' which is a message people often send back to you when you ask them for technical help
/R T F M/ Read The Fucking Manual (always abbreviated, sometimes bowdlerised to "Fine" or "Friendly") An (unhelpful) guru's traditional response when someone asks a question in a newsgroup or mailing list which he could have easily answered for himself had he bothered to RTFM.
The term may also be used to indicate that you couldn't find the answer in the manual. E.g. "How do I interface Unix to my toaster? And yes, I did RTFM but the FM didn't help and I can't RTFS."
Other derived forms include RTFAQ, RTFB, RTM, and, more recently, STFW. Compare: UTSL.