Cum-swap Garside, also known as the cumswap challenge Is a competitive game of tag where one person ejaculates into their own mouth and then cum-swaps with someone else who consequently adds their own jizz into the mix.
All contestants from around the world must then work together to get the ever growing cum-glop around the entire earth by cum swapping.
Upon arrival at the beginning country, the first occupant of said country to receive the cum will finally swallow it and thereby conclude the game.

The event is named after Robert Garside (born 6 January 1967), calling himself The Runningman, is a British runner who was credited by Guinness World Records as the first person to run around the world.
Person 1: Hey we doing the cum-swap Garside next Saturday?
Person 2: yeah! Me and Stacy has been drinking fish smoothies all week to prepare for it!

Example 2
The annual cum-swap Garside begins on the 9th of February.
Contestants from all around the world will be required to be on standby and await their turn until the games has concluded.
by Flip-flop man January 13, 2021
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When fucking a woman cum inside, then suck out your own semen only to kiss her and put it in her mouth so she can swallow it
Sara was so horny last night I gave her the Dakota cum swap!
by Mr brownstone September 20, 2021
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When a thug whips his uncut cock out and sticks it in a homeless niggas mouth and shoots his load, then allows the homeless man to do the same.
Hey dad
Yeah?
I wanna detroit cum swap this nigga
Ok cuh
by Nape rigger April 25, 2023
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The Kansas City Cum Swap or KCCS for short is a high-level, two-part procedure taking approximately seven days and three people (2 male, 1 female) to complete. The first part involves two men having rough anal sex. At the point of climax the pitcher pulls out and ejaculates into the mouth of the catcher. The catcher then spits the semen into the mouth of the pitcher who then performs a "reverse felch" in which he blows the semen back into the anus of the catcher using a silly straw. This must all be done quickly as the anus of the catcher is (as required for the second step) badly bruised and will swell shut. After seven days (and a steady diet of anti-diarrheal medication) the catcher's anus finally relaxes and prolapses at which point he uses it like a dildo and sticks it into the vagina of the female. Once it is fully inserted the male then farts with enough force to fully expel the semen (and generous amounts of fecal matter) while simultaneously the female performs a "reverse queef" to suck the babybatter into her ovaries with the hopes of producing a healthy dbox offspring.
Bob: So last Summer Martha and I vacationed in Truck Stop, Missouri and did a Kansas City Cum Swap with a trucker named Jim.

Dave: No wonder your son is such a fuckin dbox.
by Lord069 August 23, 2011
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A machine that will swap cum from one penis to another. It hurts, at first. But you will soon get over it.
by chrissypren April 1, 2021
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