Last night's How I Met Your Mother introduced us to a new archetype in American pop culture, following on the heels of the Cougar and the Manic Pixie Dream Girl before her.
"The Woo Girl is a type of young woman who, like the cuckoo bird or the whippoorwill, gets her name from the signature sound she makes," says the show.
And that sound is "WOOOOOOO!!!!" It is usually preceded by a round of shots.
Woo Girls are often found in their natural habitats; any bar named O'Flanagan's, McDrunkey's, or have a Western theme/mechanical bull. They can also occasionally be found anywhere else that there's an open bar. They can usually be identified by their low-cut shirts and their requesting of bad jukebox music.
The show is often right-on about urban culture, and New York, specifically. Watch the clip below, as Robin tries to explain why Woo girls woo. Hint: It's because they're secretly dead inside.