When Tom wanted to have an audio cuddle party and that chick called up with that really, sex-kitten type of voice. He said he had to hang up on her, didn't exactly give a reason but it was obvious. That was funny.
Also, not a Tom vs. a caller moment but a John vs. a caller moment - Jimmy Crespo. My god, when he called that kid a schmuck I lost it (so did Tom by the way), and he follows with, "How many pull ups can you do?" Ridiculous. Hilarious.