Just got back from the local big box Walmart with a can of Reddi-wip Sweet Foam Coffee Topper, anxious to use it on a cup of illy Extra Dark Roast. I followed the directions to a T and got a thick layer of sweet foam on top of my coffee.
The first few sips were mostly foam, with a bit of coffee struggling to get through. I eventually got a 50/50 mix of foam and coffee, but by that time I'd drunk most of the foam. As you can guess, the foam didn't last long.
Interesting concept.