No-Holds-Barred Contest

Sometimes, fights have rules. These rules can be manipulated through things like the use of preposterous technical clauses. Other times, however formal things may be, the fighting doesn't actually have any rules at all. Last one standing wins. Use anything you can think of to make it happen.

See also- Trying to Catch Me Fighting Dirty, There Are No Rules.

Anime

 * Milly in Code Geass loves organizing highly elaborate contests like this with absurd high-stakes prizes. Once, it ends up going a little too far when one character attempts to use a mecha to win one.
 * Played with for comedy in an episode of Full Metal Panic!? Fumoffu when the Karate Club's idea of "no holds barred" combat comes into violent conflict with Sousuke's. Hint: the Karate Club's definition doesn't include guns, tear gas, or hand grenades.

Film
"Butch: No, no. Not yet. Not until me and Harvey get the rules straightened out. Harvey: Rules in a knife fight? No rules! Butch: (kicks Harvey in the 'nads) If there ain't no rules, let's get started. Someone count 1, 2, 3, go. Sundance: 1, 2, 3, go! Butch: (knocks Harvey out with a two-handed punch)"
 * Butch Cassidy and the Sundance Kid


 * Mad Max: Beyond Thunderdome
 * Lionheart
 * No Holds Barred (Imagine that)
 * The first X-Men movie has an example in the cage fight that introduces Wolverine, again toyed with a little: "Don't kick him in the balls." "I thought you said anything goes." "Anything goes, but he'll take it personal."
 * In the 1975 version of Rollerball, the championship match basically boils down to this.
 * Serenity, the final fight between Mal and the Operative.
 * The second Best Of The Best movie indulged in this and had one member of the martial arts team killed in such a match, pulling his friends into it too.

Live Action TV

 * On News Radio, Joe and Matthew compete in an Ultimate Fighting match for charity. Matthew's strategy: tickling.

Professional Wrestling

 * No holds barred matches, obviously. Goes by many other names as well, like Falls Count Anywhere, No Disqualification, Hardcore, Extreme Rules, ect.