Apparently, when you put a cup of oatmeal in the microwave for 10 minutes instead of 1, the oatmeal just expands to a point of bubbling over the rim. It doesn't seem to explode all over the entire microwave - just the cup it's in and the surrounding microwave base.

Worth noting - this is not an easy cup to clean. The oatmeal is very hot when removed from the microwave, and dries onto the cup very quickly. Recommended steps: Get what you can gone with a paper towel initially, then (if concerned about the cup cracking and shattering) wait for the whole thing to cool. Then soak in water until the oatmeal is pliable, and remove the rest with a towel of cloth or paper.