During anal sex, the person that is doing the penetrating and thrusting is the one that is doing the "knocking," and the anal opening is, obviously, referred to as the "back door."
by Zeeky H. Bomb March 19, 2005
Get the knocking on the back doormug. A condition in female humans wherein their breasts are too far around to the front of their chests. Clinically referred to as Crowded Cleavage Condition.
Opposite of bow chested.
Opposite of bow chested.
Dave: "Man, is Cindi knock chested or what?"
Kevin: "Way. I feel like her tits are always staring at me."
Kevin: "Way. I feel like her tits are always staring at me."
by Connie Lingquist November 4, 2010
Get the knock chestedmug. to fuck a girl in the ass, and right as you're about to cum, you punch her in the back of the head so she tenses up.
by Deez Nutz May 30, 2004
Get the knocking out the donkeymug. 
IE: you get your girlfriend pregnant and you did not use protection.
School of hard knocks says: Use protection because now you have another mouth to feed.
School of hard knocks says: Use protection because now you have another mouth to feed.
by lilshawn June 14, 2004
Get the school of hard knocksmug. "I went on a date last night but the sheila didn't put out so I had to go game and knock the top off it"
by Digger111 June 13, 2016
Get the Knock the top off itmug. n. when a man attempts anal sex without requesting verbal permission. Often involves either precursory acts such as foreplay (rimming, anal fingering) or preceding acts (spreading of ass checks, tapping head of penis on anus, pushing the tip of the penis onto the orifice without full insertion) to signal one's attempt at anal intercourse.
After doing it doggystyle with Jackie, I started knocking on the back door. She didn't object so I totally stuck it in her butt until she screamed.
Richard Johnson kept knocking on the backdoor last night in bed, but I told him to stop since I barely know him.
Richard Johnson kept knocking on the backdoor last night in bed, but I told him to stop since I barely know him.
by calisp August 1, 2013
Get the knocking on the back doormug.