On a 7-9, she'll do it if you turn her on.

You pull Jenna close to you and kiss her deeply. Jenna moans into your kiss, and laps at your tongue. After a few minutes, you break the kiss, and pull your t-shirt off over your head. Jenna smiles at her sister as she runs her hands over your firm, tanned chest. Still holding Jenna close to you with one arm, you reach out for little Jessie with your other hand, and pull her in close too. Jessie gasps, blushing cutely, and joins her sister in caressing your chest. You kiss Jessie softly on her lips. then again, harder, longer, pulling her closer to you. You go back and forth between Jenna and her sister, kissing both of them passionately. Then you sit back, and gently push them together in your lap.

Jenna and Jessie smile at you, lean in close to each other, and start kissing each other. Gently at first, tenderly, with lapping tongues and cute little giggles. Then more passionately, open mouthed, touching each other, caressing each others' long dark hair, and squeezing each others' pert little tits. A few people in the park stop and look at you, shirtless on the picnic blanket, with two hot young sisters making out in your lap.