A man the anal sex position where the dick is up the asshole in a dick-riding fashion. The dick-riding partner is on the top of the other who's belly is facing up while the dick is up the ass. The "poop" in "poop jockey" comes from the shit that is on the dick from the anal penetration.
"Damn you're riding that man like a poop jockey"
A man who performs anal sex with another man for sexual pleasure.
That guy is definitely an ass smashin poop jockey