Note to those around Entourage star Jeremy Piven: Don’t mention that whole mercury-poisoning thing, advises. The website reports ex-Saturday Night Live star Chris Kattan apparently got a dose of Piven’s rage behind the scenes at MTV’s It’s On With Alexa Chung last week.

According to the NY Daily News, the pair got into a shouting match when Kattan asked Piven: “So, what are you here to promote, your Broadway play?,” referring to Piven’s excuse that he had mercury poisoning when he left the show Speed the Plow in December.

Piven responded with a dig at Kattan’s best-known character on SNL: “Well, what are you here to promote? Mango?”

Though Kattan thought Piven was joking, a witness says Piven stepped up his insults. “(Kattan) said ‘Whoa, man — I thought we were just fooling around here,’” to which Piven allegedly responded: “I’m getting sued for that s—t ... It’s not funny.”