It is kind of hard now unfortunately but I think my favorite call of all time is from 11/29/05 [Best Show Gem: January 11, 2010] when a 13-year-old named Mac, who is talking about Aerosmith and a music encyclopedia book, gets a call from Jimmy Crespo of Aerosmith. Mac thinks Crespo is a fake caller but Crespo's knowledge of Aerosmith kind of turns him around. If you have not listened, go the archives--Mac's call starts around 1:40.
Highlights:
Mac: How many units did Aerosmith sell?
Jimmy: Units? Who are you, Clive Davis
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Jimmy: How many pull-ups can you do?
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Jimmy: Mac is a stupid name.
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Mac: ...too much cocaine.
Jimmy: For you maybe.
Mac: What?