My cat loved to hang out in my bathroom sink and he often slept there. One night he woke me up by jumping on my chest and batting me in the face, something he never did; when I stepped on the floor my feet sloshed in about an inch of water. Turns out he had managed to push down the sink drain stopper and flip up the faucet lever, and since the sink had no secondary emergency drain (which was weird because I've never seen any other sink without one) it had overflowed and nicely soaked most of my house.
At least he recognized that there was a problem and what he should do about it.