IFS in a DA-20... Small aircraft, so they paired big students w/ small instructors and vice versa. We had a fairly rotund nav-to-be that puked on every flight, per the standards. About 10 flights into the program, he was right at the beginning of a routine sortie when he turned left to inform his petite female instructor of the impending disaster. The only words he was able to get out of his mouth were "I think I'm gonna be......." They immediately performed one to a full stop, shut down, and she marched straight to the step desk. A large group of us were getting ready to step when she walked in, dripping head to toe, said she was done, and left.