I once got a meatball sub from Blimpies pre-ski. after ordering said sandwich the man behind the counter pulls a plastic tube out of a freezer, places it in microwave. After 5 minutes he pulls the tube out of said microwave screaming "Jesus fucking Christ this shits hot, where the fuck are my oven mitts!" he then proceeds to cut open said tube and squeeze the contents onto a loaf of bread. what we now have is a piece of cheep bread covered in what i assume is really hot ketchup and an attempt at meatballs, with some "Parmesan" on top of it. I ate the sandwich, because i paid for it and was hungry. on the rest of the car ride, I was feeling a bit of a rock in my intestines forming. Get up to mountain. run one: finish run, feeling OK. get on swinging lift: sell Buicks all over the racecourse below chair. get to top of chair, ski down as fast as possible to toilet. I then proceeded to let the Niagara flow for 12 minutes.
tl,dr: Don't eat microwaved things from bags before skiing