Referring to the exchanging of bodily fluids between two guys through the course of anal sex.
One may say this in a joking way to ones chums to gain a chance of laughter, but has really got, what the youth of today call "issues" and should stop being so "batty"
Mike says to Patric
"mate forget about going to The Hart, lets go to that gay bar - The Birdcage. After all, one up the bum no harm done." This is when Patric would probably knock the shit out of Mike, grab a beer and go to The Hart.
by Mike June 6, 2003
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When you go too school and they ask you " what is 3x*9g/7^r.33333333333333333333" then goes over to your desk and says "HURRY UP LARRY THE ANSWER IS DO AT THE END OF CLASS"
Teacher: " what is 3x*9g/7^r.33333333333333333333"

You: Shut up, my one brain cell is working very hard right now!!!
by greencreeper244 March 20, 2018
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To like sb's comment on a social networking site such as Facebook.
"People constantly seek attention and validation through one-upping people's comments"
by MFRO June 19, 2017
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When your massive dong goes from a heads down to a heads up position, you gotta let that honey pie know you just got a one up.

Check to see if she wants that mushroom power-up
Damn horbino, yo cleavage just gave me a one up. Grab a wheelbarrow and help me transport this mushroom load to bitches in need of a mushroom tip infusion.
by Mushboom August 12, 2021
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To deliver a turd so large that you have to stand up off the pan in order to achieve maximum length.

To leave a turd standing up like a telegraph pole when you drop it.
‘Mate you were a long time in the toilet’
‘Yeah I’ve just stood one up, you should see it, it was magnificent
by mrbruceman December 13, 2022
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To be owed a favor or to be ahead of someone in something both parties have agreed to as a

Competition
Dude you beat me again you’re up one

I’m still up one on the favors you owe me bro
by Imagetry February 21, 2023
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