I remember absent-mindedly making coffee with the tea I'd just brewed. It wasn't very nice, though I suspect that a large part of it was simply that the result was unexpected. Then again, the fact that is isn't a thing suggests that it's genuinely not very pleasant.
Talking of which, one of the worst chocolates I've eaten was courtesy of the usually excellent Chocolate Tasting Club. Apparently everyone told the chairman "no! That's a really terrible idea!" but he insisted it was a fantastic idea, so the thyme chocolate became a thing. It was awful. The only chocolate I've tasted that was even worse is Hershey's, which is sort of vomit-flavoured.
I've occasionally tried all day drinking when it comes to beer but I tend to fall asleep after five or six pints.