devil's doorknob 

Also known as the clitoris

I bet that bitch Stacy is sitting at home alone, ringing the devil's doorknob as we speak.

devil's doorknob by _Nolski April 10, 2016

Curie's doorknob 

A sexual act in which a (preferably mildly to moderately radioactive) rod is inserted into the anus and rotated.

Yeah, me & my chick went out to Marie Curie's house a while back, and she let me turn her Curie's doorknob, if you know what I'm saying!

Curie's doorknob by Altoids? August 14, 2018

doorknob-sucking lips 

Exaggerated lips on the mouth of beautiful woman which appear to entice a male member.

"She's got a nice set of doorknob-sucking lips, and I wish she'd just 'plant them tulips' on my crank."

doorknob-sucking lips by Etch September 8, 2006

slick as snot on a doorknob 

Very slick indeed.
Phrase used to convey:
1)A sense of elegant suavity
2)A smooth, dashing je ne sais quoi
3)Class coming out ones' ass

Impressed Socialite #1:"I say, did you see how William butt-fucked that bunny-rabbit without soiling his cummerbund or spilling his green tea?
Impressed Socialite #2:"Yes, he's as slick as snot on a doorknob."

slick as snot on a doorknob by Kieran Le Petomaine November 26, 2006

sock on the doorknob 

Tying a sock on a doorknob to signify to others that you are inside the room having sex. You do this as an international sign to say: do not enter. If you do, you will regret it and I will be embarrassed.
Sometimes called a doorsock

My roommate saw the sock on the doorknob, so they knew I was in there having fun with my partner.

sock on the doorknob by Strongly Opinionated Erin January 13, 2018

Sticky Doorknob 

Pouring something sticky (beer, soda, bodily fluids, etc.) on to someone's doorknob so that they grab a sticky doorknob.

Kyle and Tom were being annoying as usual, so I left them with a sticky doorknob.

Sticky Doorknob by bigreddoorknobs January 12, 2021

Slippery Doorknob 

Where a man or women puts a mass amount of lube on their fist and the other man or women then proceeds to sit on that fist while it glides gently up their booty.

Curt: My buttholes feeling a little tight right now.

Austin: Well I can fix that right up with a slippery doorknob!

Slippery Doorknob by pattyrick2313 March 17, 2010