Because it worked the first time I did it, I've been putting the Quaker Oats and the milk into a Tupperware, bringing it to work and microwaving it here. My initial fear that the Tupperware would leak was soothed by several weeks of non-leaking.
Yeah, well. Glad my lunchbag is nylon and my sandwich was in a baggie. The milky mess was annoying to clean up but not office-destroying.
I think I'll start bringing a half gallon of milk to work and leaving it in the fridge.