Dude you're SUPPOSED to put the can up-side down in the hot coals and wait for it to launch across the campground like a mortar shell from the heavens. Then you go hungry, but laugh your ass off at how fucking cool your idea was.
Yeah, yeah, I did that one too many times already. Sux being hungry all the time. I just eat it cold now... Call me a caveman.
The other thing that works cool is to toss your empty can of OFF! in the fire and wait for it to cook off. Great fun!