Radio-safe substitution for jackass coined by radio personality Mike North from Chicago. Combines the feel of douchebag, jerkoff, and jackass for maximum effect.
A jagbag could be a friend dependent upon what context it's used in. It could also be used as an insult.
Word was derived from the combination of jagons featured in South Park. The episode was with earth as a reality TV show. The other portion of this word comes from a beer called Jaguar Ice with a black jaguar with florescent green eyes.