Has anyone ever tried this? I switched the regular nozzle on a can of shaving foam with one from a hairspray can, and the result was that the shaving foam now comes out under greater pressure, ie, it travels much further, much faster. Obviously the volume leaving the can doesn't increase but the jet-effect has much better slapstick potential. (I guess not all nozzles will be interchangeable, but I think they're fairly standard.)

I've always wondered how you actually do that. Surely as the can itself is pressurized when you remove the nozzle all the foam just comes out at once? Am I missing something massive?

There's a kind of removable plastic outer nozzle (The nozzle just comes off easily so you can rinse it if it gets blocked, for example.) that sits on a built-in nozzle/valve which just looks like a tiny open ended tube. If you depress that tube it releases the foam like letting the air out of a bicycle inner tube. The outer nozzle regulates the rate and direction: smaller hole, more powerful jet. You don't have to mess about with the integrity of the can itself, nor would I recommend doing so.

Edit: I've just found that If you search youtube for "How to Make a Shaving Cream Can Shoot up to 10 feet" you can find a video of a kid doing something on a similar principle by adapting the existing nozzle. You can also find instructions for making a "shaving cream bomb" as a prank, which I also don't advocate, but the video gives you a good idea of the Wam-potential.

And they said it had all been done!

Soaking the shaving cream can in hot water for 10 or 15 minutes is a quick and easy way to add to its WAM potential. The foam expands more and seems to shoot a lot further.

You can also stick a straighten paper clip in the nozzle of a shaving cream can take a lighter and melt the tip around the paper clip. When the plastic cools pull the paper clip out (should give you a smaller hole gives the effect of putting your thumb on a garden hose) and spray. Enjoy!