I have a hidden kill switch in my Blazer (it disables the fuel pump). It gives me a little peace of mind when parking in any place where somebody might think it's their right to take it. My switch is simply hard to see, not disguised.
I like the idea of the disguised/ cigarette lighter switch... it's pretty brilliant (I know it's not a kill switch, but the concept is great).
I might suggest, incidentally, that you add a decent amount of bleach to any "burnout water" formula... that gets very slippery, and very smoky... if you're into that kind of thing!