This theoretically could have happened, but I’m not saying.
If you decide to leave your water dripping for a night, because of cold weather..you know like you’ve done since you were a kid…be VERY sure which tank that drain is plumbed to.
For example, say you leave the bathroom sink dripping because the faucet is more easily adjusted to drip…IF said faucet is plumbed to the black tank, and IF you have the black valve closed (as you should), there is a very real possibility that when you stumble into the bathroom first thing in the morning and plop down on the throne you will be greeted by frigid water enveloping your hot, electric-blanket-warmed, booty.
It is not a pleasant experience and will lead to dancing (once you can move again) and a ludicrous speed trip out to the valves to remedy the situation….in your robe, of course.