I like to mess with people's heads on the phone...not to that extent, but a good "gotcha" every now and then:
(I've just called a petty bureaucrat)
Them: Department of licensing, this is Julie.
Me: Hi, Julie. I need to check on my CDL license application, please.
Them: May I have your name, please?
Me: B-but Julie, if you had my name you wouldn't be Julie any more, you'd be Joe!
Them: <splutter> I mean would you give me your name?
Me: OK. Now Joe, I want to..
Them: No! I mean would you
tell me your name, please?
Me: Oh. My name is Joe, Does that mean you want to go back to being Julie?
Them: Er...yes, please. <sigh>