Being an adopted child of no blood relation to one's adopted parents, the act of having sex with a relative. It has all the flavor of incest without the incest, technically since there is no close biological link between the two (or more) individuals partaking in the act.
Mike: Hey, Nick, did you hear Brian fucked his older sister?
Nick: Awww, gross, dude!? What the fuck?
Mike: I know, but technically they're not related. Brian is adopted; so, it was diet incest.
Nick: Awww, gross, dude!? What the fuck?
Mike: I know, but technically they're not related. Brian is adopted; so, it was diet incest.
by jmw87 October 1, 2010

by The Elias June 2, 2016

by Lil Carrotcake November 6, 2018

Person 1: Whoa.. why is he so in love with his cousins?
Person 2: That’s just Pornstar, he’s an incest expert, straight from Alabama.
Person 2: That’s just Pornstar, he’s an incest expert, straight from Alabama.
by Python3 July 28, 2019

“Good golly! Cheryl , is that cherry incest you’re wearing?”
“Why yes it is, Karen. I bought it from JC Penny”
“mmm the sweet smell of cousin fuckin’ under the cherry tree”
“Why yes it is, Karen. I bought it from JC Penny”
“mmm the sweet smell of cousin fuckin’ under the cherry tree”
by cherry tree Betty June 14, 2019

by jharrison3452 December 31, 2015

by ap3419 November 30, 2013
