Polite euphemism for anal sex, just crying out to be written into an updated Carry On film based around DIY enthusiasts.
Jack Douglas : "I'll be finished as soon as I've knocked her back door in and put me extension up"
Sid James : "Hwar har har!"
by TC Raymond July 21, 2005
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While wearing a bomber green condom you Lube a girl's butt up with Hellman's mayonnaise inline her butt cheeks with slaw then violently anally penetrated her
Oh yeah I was back behind the grocery store the other day giving this girl The back door Ballard County slaw dog.
by Cairo Jerry July 12, 2019
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A dirty way of saying surprise butt-sex.
1.Waffles: Hey Dwarfo, I'm gonna cum to your house and knock knock on the back door. If you don't answer, I'm gonna bang bang!

Dwarfo: Yeep! I hope it isn't too surprise!

2. What rapists say to little kids when they are gonna butt-rape them.
by Dr. Dirty August 15, 2008
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When two men line up anus to anus. The men then pivot on the right butt cheek of one man, and the left butt cheek of the other. They crawl apart as though they are a barn door opening. Then a third man anally penetrates the two men one after another.
Workout bro: Yo how's the barn door back coming along?

Sexual deviant: I'm still looking for two more guys.
by Barndoor bro June 25, 2017
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next to impossible spare while playing video bowling
7-10 split and as the ball careens down the lane, in order to encourage the ball to get the spare you say "back door santa claus"
by dtanger22 August 7, 2010
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When you’re fucking a girl doggy style and then it slides out of her vagina and with a seemless transition slides in her ass. This is very hard to do without any prior engagements loosening of the ass hole.
She gave consent for vaginal intercourse but when Kevin did the doggy to the back door she said she didn’t consent to anal. She told the police and Kevin ended up getting questioned.
by The Duke of Price Hill March 4, 2019
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