Usually reserved for jobs or activities that require hardhats. "Two turles fucking" is when a person takes off his/her hardhat and swiftly brings it down on top of another's hardhat still on other's head. It doesn't hurt like being cracked in the head, but it stings a bit and jars one's brain.
Worker: "Hey, ever heard two turtles fucking?"
New Guy: "No, what do they sound like?"
(Worker executes "two turtles fucking)
New Guy: "Owwww!"
New Guy: "No, what do they sound like?"
(Worker executes "two turtles fucking)
New Guy: "Owwww!"
by Pork King October 14, 2005