imagine spontaneous combustion.
just imagine yourself having a day out with your friend as usual. then, you see her bursting into flames, with no apparent reason.
just imagine.

I tell you, it's damn creepy
any time now, any one of us, any of our friends can just burst into flames o.O
oh my, just think, later your friend is reduced to a pile of ashes! :O

http://en.wikipedia.org/wiki/Spontaneous_human_combustion