A hunger comparable to that which comes with being stoned. Elevated by stress, exam munchies are usually at their worst on the day of the exam, causing you to consume ridiculous amounts of food.
Eli: Man, I think I'm going to barf all over my final.
Jim: You sick?
Eli: Nah, I had a crazy case of the exam munchies. I ate four packs of cookies and a box of corn pops before leaving.