Happens more often than you'd think. I'm a general contractor and it's a pretty common occurrence.
I was once in a law office on maybe the 60th floor of the US Bank Tower in LA (third tallest building west of the Mississippi) and went to use the restroom. Sat down on the toilet (won't get graphic) and immediately felt like I had a fever and was uncomfortably warm. Soon realized the whole toilet was warm and that the water in the bowl was actually hot. Someone had obviously done some service or replacement of plumbing in that restroom and had reconnected the toilet incorrectly (which is a pretty tough task considering there shouldn't even be any hot water lines anywhere near that part of the restroom).
