Oncest

When the two versions of the main antagonist (The Onceler) in the Dr. Seuss book, The Lorax, are having sexual intercourse with each other.

I, the creator of this definition, had recently found oncest fanart on my TikTok For You Page because once my friend sent me a video as a joke and now it's all over my For You Page. I was so disturbed, I cried into a piece of stale bread.

by XAXAXAXXAXAXXAXAXAXXAXA June 19, 2023

oncest

slang for "once"

Would you do as I tell you for oncest!

by aarby08808 February 4, 2018

oncest

when your on top of your family memebers but not fucking them

“that’s incest”
“no that’s oncest”

by bitchybitch29 July 5, 2020

oncest

when one sibling is on top of the other

this isnt incest, this is oncest.

by hoepp69 July 5, 2020