Thuck Your Cock
Usually with a screengrab of someone with their tongue between their teeth.
The joke itself is a reference the 'Raging Bullwinkle' sketch from the HBO comedy series "Hardcore TV." A takeoff on 'Raging Bull' starring the legendary moose in DeNiro's role, it had a scene where Bullwinkle's wife taunts him, declaring she even s*cked Mr. Peabody's cock -- to which Bullwinkle looks into the camera and exclaims "You thucked Mither Peabody's cock??"
Later on, it was changed by TheGrayZombie, excluding the Peabody-reference and making it more generalized. Though it has rather notoriously been linked with him ever since.
"Thay, can I thuck your cock?"
"OK, drop it, don't go any further. Sorry I started that caption."