When two men are engaging in anal sex, and the man who's inserting his penis' balls slap against the other man's anus, to an extent where a fudge-like coating of feces over both nuts is created.
Also, a kind of coffee.
"We were going at it so hard I had a double nut fudge"
"Are you going to have the double nut fudge
, or try the Brooklyn brew?"