RTFM is an initialism for the statement "Read The Fucking Manual". This instruction is usually given in response to a question that can be answered easily by reading relevant documentation, and suggests that the inquirer may be wasting people's time.
In computer technical support it also commonly refers to "Reboot The Fucking Machine," an aptly prescribed first line of troubleshooting that has been widely recognized to solve a great majority of computer problems, particularly on the Windows platform. It implies exasperation at minimal problem-solving initiative.
To avoid the use of the expletive "fucking" in the statement (which is offensive to many people), the "F" is often translated as "Fine" or "Friendly". Alternatively, the "F" can be dropped entirely and the initialism rendered as "RTM" (Read The Manual).