Defending yourself (or others) by seeking revenge for somethingdone to you (or others).
Ex. 1- Don: Jack Bauer and Batman just went on a mission to find and apprehend the crazy terrorist who bombed Gotham Los Angeles Plaza.
Bill: Yeah, they both seek defengeance for what happened. As long as the terrorist are out there we aren't safe.
Ex. 2- Whenever a member of a gang sees someone from a rival gang, he's obliged to defengeance himself. He must defend himself from a possible attack (whether immediate or in the future) by seeking vengeance on the rival gang member for all the pain the rival gang has cause him. It's a never ending cycle.
Ruler of Lake Titicaca. Rumored to have a bunghole that gets very angry if it does not receive toilet paper. Cornholio the Great is often seen walking around with his shirt over his head and his hands in the air, chanting songs about his power, and his bunghole.
"I am Cornholio! You do not want to face the wrath of my bunghole, for I need TP!"
Butthead: Shut up, Beavis! (uh huh huh huh)
Beavis: Um, okay. (heh heh heh heh).