"One captain came up with the idea where they would just pick out a white kid and a black kid and let them fight in a cage for five minutes once a month, and that's how it was done. I had to fight like this on two different occasions. Even though I didn't want to do it, I knew that if I didn't, the guards would just take out their sticks and beat both of us senseless. So I fought."
Even though that's clearly a foreign-object penalty.
The whole thing, Yarris says, was a misguided attempt to release racial tension in the yard. If it sounds too horrible/ridiculous to be true, note that in the California prison system, it was discovered that the guards were betting on these "gladiator fights" between inmates (there they'd do it with members of rival gangs).
Yarris says there were other, entirely pointless cruelties as well, like guards plain ol' messing with you for their own amusement. One perennial favorite was the old "fake visit from mom." They'd start, he says, by telling an inmate he'd gotten a surprise visitor. Since that can be the bright spot of a convict's whole month, it made for easy bait: