Just along for the ride.

Dina hops up which causes her dick to push against you. With your hands now grabbing her tits, she goes off at a fast pace. Her hands caress your thighs which rise up and down on hers as she runs.
"Can you cum while running?" You ask as you knead her boobs.
"I could, but it could get messy for you."
"What do I care? I'm naked. You are the one still fully clothed! Afraid to show some skin?"
"Nope. I just havn't needed to yet. Are you saying you aren't turned on by me even though I'm fully clothed? The slickness of your dick begs to differ!"