EW!

This single finds Jimmy Fallon, the host of NBC's The Tonight Show, teaming up with Black Eyed Peas frontman will.i.am. The song is based on the show's "Ew!" series, in which Fallon and a guest dress up as as a couple of teenage girls who are constantly disgusted by all the things around them. The pairing with will.i.am marked the first musical collaboration in the series – the previous "Ew!" sketches were spoken-word only.

Fallon told the On Air With Ryan Seacrest radio show how the song came about: "So, we had will.i.am on the show about two months ago," he explained. "Backstage we're talking and he goes, 'I really like that sketch that you do, "Ew!," where you dress up as a 15-year-old girl and everything is like, "Ew!"' I said, 'You know, we're doing it with Taylor Swift this week, but next time you come back, I'll write you in and we'll do one." "In three days, before the writers [and I] could even write any lyrics, he sent me a full-on produced song," Fallon continued. "So then he flies to New York, I go to a recording studio, we tweak it a little, and I write some raps for myself. So this is me rapping, as well, which is sad."

Proceeds from sales of the single go toward the SeriousFun Children's Network and will.i.am's i.am.angel Foundation.