RTFM - Read the F**KIN' Manual Tshirt.
This instruction is usually given in response to a question which the responder knows or believes 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. It implies exasperation at minimal problem-solving initiative.
This "RTFM" design is printed on a 6.1 oz. 100% Gildan Cotton tshirt. This tee shirt is extremely soft and preshrunk.