New “Tonight Show” host Jimmy Fallon has a recurring sketch called “Ew!,” where he and some good-sport guests dress up as teen girls and put on a show in their basement that’s more than a little reminiscent of “Wayne’s World” — if Wayne and Garth were 14-year-old girls.

This time around, “Neighbors” stars Seth Rogen and Zac Efron got in on the fun. Rogen as a young girl — complete with very thick beard — grunting the world “ew” over and over is terrifying. That’s going to haunt our dreams. Efron, however, makes quite the fetching young lady.

Below, watch Rogen’s interview segment where he promotes “Neighbors.” “We found a lot of our jokes were about genitalia, so we had to balance that out with emotion or else it gets way too skewed toward the genitalia side of things,” he says.

“Neighbors” opens nationwide Friday (May 9).