- Cuddy: Other doctors actually use their offices for crazy stuff like seeing patients. Not throwing a ball against the wall and calling it work.
- Wilson: It's his process. That ball saves lives!
- — Let Them Eat Cake
B.O.U.O. (ball of unknown origin) is the red and gray ball that House owns. It's speculated that it's a tennis ball, or a dog toy. The ball has a needle hole for inflation or deflation.
House will entertain himself with the ball by throwing it to himself, bouncing it off a wall, flipping it around with his cane, etc.. House uses it most when trying to think about his case, and in tough situations.
House has affectionately referred to it as "Ba Ba" and "Bally".
In Acceptance, the ball is red and red, instead of red and gray.
In Everybody Dies, Chase becomes House's successor and starts using the ball, just like House did.