
I would hope you didn't witness it, otherwise you would be in your 80's right about now.
But the amount of a reactive chemical that would have to be in the body for it to have a exothermic reaction would be probably 1000 times the normal dose of DNP. (probably higher than that) But as I said before, I don't even know if DNP causes an exothermic reaction with water. Because it is stored with 15% moisture already. So I doubt it would have that kind of reaction with water. There is a heat increase when most things disolve, but if something is easily disolved, (like salt in water), the amount of heat released is almost immeasurable.