Short for Dragon Ball Z, it is an anime
that is both the next generation of the show Dragonball where the characters are all-grown-up, and either adored or spat upon by anime fans(real fans see those that like it as juvenile). The second reaction is based on several of DBZ's characteristics:
1: plot. the large majority of any DBZ episode (and theres a LOT of them) is that the planet its threatened with extinction by one evil guy or another, and it is the job of Goku (main character) and his friends to stop them.
2: temporal realizim. Not only do they try to save the worlds that each have 5 minutes till detonation, but they always manage to stretch those 5 minues across 10 episodes or more, becoming VERY tedious for anyone to watch at any closer intercal than once a day or once a week.
3: character originality. The premise behind 90% of the characters battle styles (once again, they battle almost all the time) is that they use a lot of primal screaming and "getting pumped up". This is agonizing enough if it werent for the fact that time is so dilated that a character will be twitching and screaming in gathering energy for a whole episode(often more than one), all the while using the same animation from last week.
Real anime fans don't watch anything on the Cartoon Network, especually DBZ.