Random law of the brewday #267: You will inadvertently leave some tap or valve open at a critical point in the process.
Especially if it will pour hot wort/water into your sock/boot
...or your crotch. (First runnings...down my leg)
I'm not even gonna ask what your crotch was doing near the draining wort...
Check, I have done #267 the scalded foot. Only it was hot water on my very first all grain while dumping in strike water. A brown ale that ended up infected...
Sadly I was wearing sandals? or crocs? maybe chuck taylors? or some other such improper footwear! YeeOUCH! That was a blister!