Indicate your intentions through some elaborate hand gestures

You wave your hands in the air, signalling into the air and at your crotch while shaking your head vigorously. After a moment, you pause, assuming your message has got through.

The girls stare at you, eyes wide.

"It's a psycho," the small girl whispers.

"It's a boy, though," the girl with braces whispers back.

"Um..." you gulp, trying to speak. "I thought you were really beautiful, so I thought I'd ask you if you wanted a quick, you know, one night stand. And maybe I could keep your underwear."

There's another pause, as the nerds stare at you. Soon, the big-chested girl raises her hand.

"Uh, yeah?" you ask.

"Excuse me, which one of us are you asking?"

You fumble to point, before realizing you should probably respond with words.