Double Butt is a goat that is notorious for having two anuses. Gene goes on a search to find him in "Stand By Gene" along with Tina, Louise & other kids they meet at Wonder Wharf. He resides on a farm off Route 6.
Gene first hears of his existence when under the pier overhearing two men talking about him. He leads the kids on a journey to find him, but is at first apparently unsuccessful after seeing a "one-butted goat." After Gene turns his back to the pen, he comes into view of the other kids as Gene turns around and sees him. The farmer is at first hostile, but this is just a character he does which he calls "The mean, old farmer." After this, he lets the kids pet Double Butt.
- It can fart simultaneously, a phenomenon that Gene calls "Fartmony."
- In addition to having two anuses, he also has two tails.