For one person to put their face down near another persons anus and make chomping motions with their teeth while the other person deficates.
Person 1: "Dude so me and my wife totally tried something new last night."
Person 2:"Oh yeah? was it the chumchipper?"
Person 1: "You bet."
Jack was dropping pole with Martha's dirty fudge pudge, when he thought a chumchipper sounded delightful. Martha was open to the idea, so jack smiled and didnt leave a poo nugget unchumchipped.