The OED definition, for those unfamiliar with the concept:
a situation in which a platonic relationship exists between two people, one of whom has an undeclared romantic or sexual interest in the other:
"I always wind up in the friend zone, watching them pursue other guys"
I could go on and on about the term (and the folks whom it describes, though everyone who has ever pursued a romantic relationship could be said to have been placed in the friend zone at one point or another), but Slate's writeup takes the cake:
Unsurprisingly, the masses are fond of this new term. (And let's be honest: While men and women of all sexual orientations get crushes, the friend zone is mostly a straight-male phenomenon based on the widespread sexist belief that straight men can never truly be friends with women without having an ulterior motive.) It’s so popular, in fact, that it is now being put in the Oxford English Dictionary, a sacred tome widely believed to be both a better dictionary and a better step stool than, say, Merriam-Webster.
All this demonstrates what Jane Austen was trying to tell us 200 years ago: Sometimes it doesn't pay to let a guy down easy. Many a woman has uttered the phrase "Let's just be friends" on the theory that something a little more direct would result in an angry reaction. But really, even if your suitor goes so far as to cough up a word that starts with a b or even a c, is that really worse than having him go on Tumblr and write self-pitying posts about how the woman who belongs to him refuses to accept her fate? If you suspect that you're dealing with a guy who is comfortable with the term friend zone, then there's no reason not to be blunt in your rejection, preferably by saying, "I could never be with a man whose beard smells like Cheeto dust."
Seriously, check out Slate's post. There's a ceramic pony wedding topper image that's incredible.