I was fortunate enough to hear (in the course of my job) some of the voice acting sessions Tim Curry did for a computer game based on the Wild Thornberrys. The voice director was Charlie Adler, who is certifiably nuts.

Listening to Tim Curry's urbane, cultured voice bounce off Adler's zaniness was just fantastic. Some of my favorite quotes:

"Okay, here we go, let's roll this motherfucker."
- Charlie Adler, upon starting the recording session

(Adler has one of the most foul and yet funny mouths I've ever heard. And the things he got the voice actors to say...once he managed to get Jodi Carlisle, the voice of Marianne Thornberry, to read the line "Very well done" as "Very well hung". On tape.)

Upon being told he would be voicing affirmations (lines in the software that tell the child they are doing well) Curry quipped "I thought American children had way too much affirmation already..."

"God, it's tough being an idiot for quite this long."
- Tim Curry, after a few hours recording