The sexual act of fingering one's asshole, whilest holding a fishing hook in the other hand.
David: Can we Huck Finn?
Lindsay: I don't want to be Huck Finn'd, I'm afraid of fishing hooks!
(1) (noun) fuck buddy. See also huckleberry friend
(2) (verb) to take someone on as a fuck buddy, or to have sex with ones fuck buddy. See also huckfinning
"No dude, he's just my huckfinn."
"He's hot but dumb as fuck. I just want to huckfinn that shit."
When a man penetrates a woman anally while immersing her head in a toilet bowl full of his fesces.
"You wanna Huck Finn tonight?"
"Your shitter or mine?"
"You wanna Huck Finn with me tonight?"
"No, didn't you eat beans today?"