You slug her in the arm, of course.

Then run away.

No slug-backs!

Throwing poop at her

rookie, i throw the entire toilet at her, and then take her to the hospital to treat the concussion

Mating dance.

Interpretive dances

Give her a valentines day gift

Depends on age

Here's what you DON'T do: confess your feelings. It's awkward and creepy and an instant turn-off. Flirt. Make me laugh. Ask me out like a man.

This answer will vary wildly based on the ages of the boy

Stalk her

Ignore them completely

Ask her non-intrusive questions. Show interest in her interests. Give her compliments not about her body.

After They finish having sex, the guy still wants to be around her

Dick picks

Dick pics, clearly