pretty much the same meaning as the word asshole, but with more definition, and more demeanor, but not as evil in a sense. Jasshole is used in times of when friends or relatives want to joke with one another and not actually call the intended person an actual asshole.
Example 1: playing the card game asshole
Guy1: haha i'm president sucka
Guy:2 yea im neutral.. whos ass?
Guy3: i think Chris is
Guy1: haha jasshole gimmie your best cards.