According to
sunspiral by way of
this post by
hrafn, there exists a meme in the northeastern U.S. where motorists put signs saying "Free NP" in their vehicles' windows, in hopes that female drivers will flash their breasts at them. (hrafn's post includes some pictures she snapped of some of these signs seen in the wild.)
It apparently originated from local radio shock-jocks around 10 years ago, and has indeed outlived them (for this was that brief era when, for some reason, there were many more shock-jocks then there are today). What I find most intriguing is that, as of this writing, there are no relevant google hits explaining this phenomenon. Googling for ["free np"] gives some sites about NeoPets, some random commercial-product giveaways, and the number-one hit of another blogger himself asking what the hell this means and noting the lack of google hits. (Fun irony!)
If sunspiral's account is corrent, then it seems that the virulence period for this meme began and ended before the Web took off among the mainstream. For 10 years it has lain dormant, with all carriers of it completely failing to spread it any further, apparently not for lack of trying.
The very notion of a pre-Web meme remaining in stasis for a whole decade is amazing to me, like discovering a stone-age tribe living in isolation.