This is the mix of the two words "jerk" and "bitch". This word was made mostly for people who cant swear in front of certain other people. Such as parents, people who dont like the language, or for people who just dont swear.
cree: "Bobby, you're such a jerkitch! why did you have to say that?!?!?"
Bobby: "Sorry cree, I wasnt trying to make fun of you."