An extrovert mathematician will be looking at the other guy's shoes.
They refuse to look at the silver lining.
The man responds "If I'm going to be im-po-tant, I want to look im-po-tant!"
Derive, derive, derive!
For me, it's gotta be Emo Phillips' Baptist joke. Although to tell it you've gotta get his execution down.
The extrovert looks at the other person's shoes.
The extroverted mathematician looks at YOUR shoes when he's speaking to you.
When talking to you, the extrovert mathematician looks at *your* shoes.
