I have, at work, a slightly-oversized coffee mug. It's from Crate & Barrel, sturdy, and a pleasant (I think) shade of green. This is, if I may digress from my point a bit, one of the ways I cope with the corporate environment. Years and jobs ago I got that mug and a complete, single set of silverware (knife, fork, tea spoon and soup spoon) specifically to bring into the office. Eating team-building deep dish pizza with plastic silverware will drive you crazy, I believe.
But the point is oatmeal. I make instant oatmeal in that mug for breakfast many days. (McCann's Instant Irish Oatmeal, Maple & Brown Sugar flavor, to be precise. An unsolicted endorsement. All natural flavors, and isn't that refreshing to see every now and then.) And if I hop up from my desk right after I finish my oatmeal and rinse the mug out it cleans up in a trice. Lickey-split. Easy as pie.
If I wait 15 minutes or half an hour or longer -- glue. There's a hard film all over the cup and tiny bits of oatmeal get welded to the bottom. It takes soaking and scrubbing to get it clean.
It seems hard not to think that there's a life lesson lurking all too obviously there. Clean up your messes right away and they're easy to take care of. I just wish I could learn that lesson, at the very least with regard to the mug.