Chuck Lorre is taking a vicious shot at an actor -- accusing him of being a drug addict who is "impossible to work with" ... but the shocker is he's NOT talking about Charlie Sheen. Maybe.



At the end of last night's "The Big Bang Theory" ... Lorre's vanity card seems to be joking about a monkey that was on the episode -- saying its "behavior became increasingly erratic, to the point of refusing to come out of his trailer to rehearse."

The card continues, "The monkey is a heroin addict. Yes, hard as it may be to believe, the monkey had a monkey on his back." It goes on to say the monkey is in detox and a 12 step program.



But after Lorre's announcement he's retooling "Two and a Half Men" without Charlie -- and Charlie's nuclear response, we gotta ask ...