When a heavysmoker deep throats a penis, and afterwards the penis is covered in black tar, mimicking the act of cleaning a chimney.
Jerome got a blow job from a 5 dollar hooker in the back alley, and upon pulling out screamed in terror as he saw the tar on his dick and realized he had been chimney sweeping that bitch.
Jane - "No John, really? Quit playing games and tell me."
John - "Sorry Jane, you're right. The Chimney Sweeper is where you take off your sweatpants, lay on your back, then roll your knees back until they touch your shoulders. This way your butt hole opens up and stares straight at the clouds above. Then I'll hover over your puckered poo packer and plunge both of my not-so-recently shaven jizz tanks past the event horizon of your turd socket. Duh!?"