So this actually happened a few years ago, but I saw another post on this sub a few minutes ago which reminded me of it.
My family and I were travelling in Indonesia for the summer and it was all going fantastic until someone reversed their motorbike into me and burnt my leg with the exhaust.
Me being me (and an idiot), I didn't realise that it was a pretty serious second degree/third degree burn and so after I was done crying I went on with the rest of the holiday, which included swimming and generally getting dirty.
Naturally it got infected and I got a fever (combined with a bout of shigella from Indonesian street food) and so when we went home I had to go to the local burns ward to get a skin graft. When I got home the heating was off so I thought I should make myself a hot water bottle and go watch a movie or something.
This is the part where I fuck up, if you don't consider not getting a burn treated a fuck up. As I'm pouring the boiling water into the hot water bottle, I manage to lose concentration and pour a generous helping all over my hand. Which then proceeded to hurt like hell. Needless to say the local burns unit was not happy to see me quite literally 40 minutes after they discharged me.
TL;DR got out of hospital being treated for a burnt leg, immediately poured boiling water on my hand.