As a warning to all, this goes into personal detail so if you don't like male genitals you probably shouldn't read.
Okay so its not really "today" I fucked up, but it happened a few years back and the memory has never left me. So picture me, ~17 years old, kinda dumb but I'd say more "naive". Well I had obviously been many years into puberty, but I decided that I wanted to start making myself more presentable...down there. It began with using some small scissors to keep things trimmed, but as some may know, keeping the balls trimmed like that can be pretty annoying and time consuming. I was living with my mother at the time and under the sink I had found a bottle of Nair hair removal. Nair is generally used for keeping your bikini line smooth and hairless, so I figured, "Hey, why not. Whats the worst that could happen?" Well you're about to find out. So before going hog wild I decided to give it a little test run, I put some on my arm, following the instructions and waiting the amount of time required. Once the time was up and I rinsed it off, the hair was still there and I was quite confused. "Maybe I need to wait a little longer," My naive little brain said to itself, "Maybe this hair is tougher than what its meant for" thinking maybe it was usually used on smaller, thinner hairs, I gave it another shot with the same results. I was tired of waiting at that point so I decided to give it a shot and used it on the flat smooth part at the base of the penis (the one right below the abdomen, I don't know what it's called but you know). After waiting the time I wiped it off, but this time I scrubbed slightly harder and in a circular motion which ended up working like a charm. After my eventual success, I felt like this was a godsend, I would be able to use this instead of scissors or a razor (which I was too scared to use at this point). So from there I move to the inner thighs, the very VERY sensitive inner thighs. Once again I wait the time and wipe it off but this time there's something different, this time it felt hot, felt like it was burning. I cleaned myself off and looked down there and on my inner right thigh there is a deep red mark where the Nair went and it did not feel great. I hopped in the shower to try and clean it and help with the burning and after ~20 minutes of just soaking it, it started to feel better. Unfortunately for me, I am currently 22 and the red mark is still there, a reminder of my idiocy and a message to anyone else who may want to try that. Needless to say I use razors now, much safer.
TL;DR: I accidentally gave myself a minor chemical burn on my inner thigh trying to remove hair with Nair. Just use a razor.