A term that can take on multiple meanings
1) An endearing term that can be used to define one of your friends who can sometimes be an idiot. Synonymous with clown
2)A total dochebag, who routinely makes an ass of himself. Used for people you have little tolerance for, even if at times their ineptitude at life can be somewhat amusing.
1) Yeah that guy over there parading around, making dumb jokes is my friend. He's such a jizass.
2) Wait you thought that guy was funny? I thought he was a total jizass, I didn't like him.
A person you hate intensely not because they deserve such hatred but because they serve as a focus for your general hatred. A healthy way to dispense with excess animosity.
Jake's not really that big an asshole. He just serves as my hate sink.