An MRE rocket is produced by placing the heating unit of an MRE (Meal Ready to Eat) in an empty cola bottle, adding a cup of water and closing the lid.
It is then either:
A. Placed at a safe distance
B. Pointed at someone unfortunate enough to be sleeping through military shenanigans
The result is the expanding of the gas within the plastic bottle, and the eventual explosion or liftoff of said bottle.
NOTE: Be prepared to run like hell if your previously sleeping victim is larger than you.