I was on ground, requested taxi and my IFR clearance to Chicago Midway. Ground told me to taxi and would have my clearance in a minute. Student was doing the run up when Ground came back with the clearance.

ATC: Cirrus 1234A read back is correct.

(a minute later)

ATC: Cirrus 1234A request

Us: Go ahead with your request

ATC: Yeah if you're going into downtown can you pick us up a Sausage Supreme Deep Dish from Gino's?

Us: Wilco!