So a friend posted a note on Facebook, mentioning that she'd told her daughter that if you wore your pajamas inside out, it would make it snow.
The boys have been all over this, as you can see (what you can't see are the underpants, carefully turned inside out as well). We even got our cute neighbor girls on the bandwagon -- it might just be a matter of telling enough people to get some critical mass to make it actually happen.