Shaving foam
Here's an interesting one:

1. Buy a few cans of cheap shaving foam, and stick em in the freezer.

2. When you can feel it's all a solid block inside, take a hacksaw and cut it open (careful with the other good inside!)

3. take your frozen block of shaving foam and place it in someone's bed/sleeping bag/underwear drawer.

As the block warms up, all the gases still in the shaving foam will start to expand out again, and with a sudden WHOOSH their entire sleeping bag/whatever will be full of foam.
(emcake putting a donk on it since, Fri 14 Dec 2007, 17:19, 5 replies)

Not quite
a WHOOSH, but could be interesting...

www.cockeyed.com/pranks/frozen/frozen.html
(TimeBelly, Fri 14 Dec 2007, 17:33, closed)

I've heard about doing this trick in someone's car. For great justice.
Is a freezer cold enough, or does it have to be liquid nitrogen?
( idonthaveafunnynickname Drink-Aware? Sure. I'm aware I want another drink., Fri 14 Dec 2007, 23:34, closed)

TimeBelly
I reckon if you did it with an industrial Makro can it might just do the job - the tesco cans are quite big, too. If I'm honest I've never tried it so I think you're right about the whoosh thing.
(emcake putting a donk on it since, Sat 15 Dec 2007, 21:06, closed)

Oh pur-lease
"The shaving cream had nearly overflowed from the bowl, overfilling it with about 12 cups of foam. It appears that the foam had expanded to about 850% of its frozen volume.

Unfortunately, this isn't very much shaving cream. This could make a real mess, but it certainly isn't enough to fill up a car."

It won't 'whoosh', and all it will do is make a ball of foam, very very slowly, about 3 times the size of your head. You Fail at reusing urban legends.
(DjArcas, Mon 17 Dec 2007, 0:49, closed)

DjArcas
Maybe if you were less of a whiny shit and looked at the comments before you'd posted you would have seen we're actually talking about it? Like I said above I'd never tried it, only heard about it.
(emcake putting a donk on it since, Mon 17 Dec 2007, 13:03, closed)