Piven and Kattan
Note to wisecracking actors booked on the same talk show as Jeremy Piven: don't mention that whole mercury poisoning thing. Someone failed to mention that to ex-'SNL' star Chris Kattan, who got a dose of that Ari Gold rage behind the scenes at MTV's daytime talker 'It's On With Alexa Chung' on Thursday.

According to the NY Daily News, the pair got into a shouting match when Kattan, at MTV to promote the IFC series 'Bollywood Hero,' sniped to Piven, "So, what are you here to promote, your Broadway play?" It was in reference to the 'Entourage' star's infamous exit from the show 'Speed the Plow' in December, citing mercury poisoning.