Custard Donut Share definition Flag Slang for anally cumming in somebody so it looks like custard oozing out of a donut. “Oh man Aedan, I gave Natasha a custard donut last night it was fantastic!” Custard Donut by DrPewnLuver October 1, 2018 0 0 Get merch Get the Custard Donut mug. Buy Now — $32.95 See more merch