there is a site (that seems messed up right now) www.cockeyed.com that defunked this myth. Yes, you could freeze it in liquid nitrogen, but how many people get get their hands on it (no pun intended). This other guy just froze it, carefully nipped off the bottom of the can, and placed it in a bowl. As it thawed, it expanded yes, but not as drastically as people are lead to believe. To see how much it will expand, just get a big bowl, and empty out a non frozen can into it, it should be a bit less than 1 cubit foot if I remember right. So to fill a car, you would need a hell of a lot of shaving cream, but I guess its doable with maybe 50-100 cans.
life is too short to have any regrets