When a person is so insanely lazy that they are even too lazy to poop and make someone else fuck the poop out of their anus.
Steve: Are you really too lazy to poop yourself?
Jordan: Yeah, just fuck it out again. I am poop lazy.
When an asshole is used more for fucking than to poop. The first necessity of the asshole is to fuck. Under this circumstance an asshole transformes into a fuckhole.
Cheese: Your asshole gets fucked a lot now doesn't it?
Salt: Yeah, true. It's actually a fuckhole.