Do you have any professors that are serious and gruff but have a good sense of humor (mild humor?)  I've found that many professors do this...

My professor is an ass.  He was all serious today, talkin bout math and how it's serious business and when class is over he'll say something along the lines of "Alright.  Class is done.  You can all smoke hash and talk badly about my country now."

One that I saw on Overheard in New York:
"Did I tell you I'm going to be a father? I'm going to be a father!"
Class: "Awwww!"
"Yep.  Had a little accident, now I gotta get married."