Throw caution to the wind

You internally say "screw it," and throw caution to the wind. You are very much enjoying yourself under the girl's direction, so you do as she says. You grind her nipple between your teeth, biting it softly and pulling on it by the nipple ring, but careful not to put so much pressure on it as to actually break the skin. The girl responds as you feared she would, getting louder and more aggressive. "Yes, you bastard! Bite me, hard! HARDER!" She also spreads her legs even wider, and grinds her pussy and clit across your thigh was surprising pressure. You squeeze her tits with both hands, one on each, as hard as you can, and alternate your mouth between her nipples. She thrusts her chest in towards you and grinds her pelvis on your leg as she furiously jacks you off. You yourself beginning to cum as you hear a "WHAT in the HELL?!" exclamation behind your spontaneous partner.