Majokko Tsukune-chan

The titular characters are both seemingly innocent magical girls who end up violently hurting their "friends" and sometimes even kill them for no good reason (and their "friends" somehow come back to life a few moments later). Also the scenarios in both shows start off harmless and end in complete nonsense most of the time.  

The biggest commonality between Pani Poni and Tsukune has to be their fast-paced, eccentric, and unpredictable comedy. I'd say Pani Poni has a more colorful cast, but Tsukune's characters are still easy to enjoy. Although Tsukune is much shorter (6 episodes, 13 min each), the quality isn't affected. It crams all the goofiness of a Pani Poni episode into half the minutes! 

Aside from the similar art styles, the shows also are broken up into short episodic stories, and have a very bizarre sense of humor. Both shows are extremely surreal, so unless you watched Shinobuden for the fanservice, you'll enjoy Tsukune-chan. 

Both comedies directed by Sakurai Hiroaki, Mojokko Tsuke-chan is reminiscent of Di Gi Charat, displaying similar bizarre happenings and absurdist humor. Fast-paced gags and crude animation abound in both of them. 

style of humour - Zany, madcap, etc. Fantasy setting short but sweet - only short, but twice as funny as most feature-length comedies