Facebook crush
A crush on a Facebook friend you barely know and weren't attracted to when you did know them. Most likely to occur when you've friended an old acquaintance who's become suspiciously more attractive over the years, due either to a particularly flattering photo or because they've now aged into a range where you could feasibly date them without being considered a perv. These factors, combined with intelligent and thoughtful posts by the subject friend, can lead to a titillating attraction for a mental projection that does not in fact exist. Such crushes are seldom viable in analog space.
I've developed a Facebook crush on Gunnar, but I'm sure it would be a disaster if we really went on a date.