During my military service, I had several encounters with car battery acid. This is a weak sulphuric acid. When using El-Cheapo Batteries, you need to keep topping them up with distilled water. Our batteries took fairly heavy wear and tear, and we had to put them into all sorts of inconvenient locations, so battery acid would often splash about.

Now normally, when battery acid splashes somewhere, you just sprinkle something related to limestone. This is not so much for safety reasons as for the nice fizz it makes.

But every once in a while, some acid splashes onto somebody's uniform (made mainly of cotton, coloured olive green). You barely notice this, so the acid just dries out.

Now you have an olive green uniform (or a nice grey dress uniform, which is even funnier) with purple splotches all over it. Turns out that sulphuric acid reacts with the cotton and colour in this manner.

The fabric looks a bit odd now, so sooner or later somebody touches a purple spot. At that instant, the entire affected area crumbles away! A moment later, you have a beautifully holed uniform...