After-Ass

When you eat or drink something that tastes good at first but then tastes like ass right after.

Ex 1.

Moiz: "This juice is good at first but then shitty afterwards .

Zach: "Dude, you've got a serious case of after-ass."

Ex 2.

"I ate this chick's ass and at the time it tasted good, but then I started tasting that after-ass when I was done"