slip her the sausage
bang her, give her the dick.  If you're Italian, you can say "the italian sausage", if you're Polish you can say "the polish sausage" or "the ol' kielbasa", if you're German you can say "the ol' bratwurst".
The first time I saw her, she gave me that old-fashioned romantic feeling, where I'd do anything to slip her the sausage, preferably indabutt.