Suggest a contest.

I grinned. Oh, I had an idea. "I think you girls need to have a contest," I told them. They regarded me with confused expressions, though they kept caressing each other's bodies.

"Contest? What sort of contest do you speak of, John?" Starfire asked, intrigued. "It's simple. The two of you are to try and make the other cum any way you possibly can," I explained. "If you cum, you lose the contest. The punishment for losing is to watch the winner have sex with me, though you can finger yourself if you really want to." I thought a moment. "Here's how it works. You each work on each other for one minute at a time. So...um...well, Starfire's the newbie, so she gets to work on you first, Raven." Raven swore softly. "After one minute, you switch places. Sound fair?" I asked.

Raven backed away from Starfire and crossed her arms. "What position do you want me in, Star?" Raven asked, dejectedly. She sounded as though she knew she was going to lose. Walking around Raven, Starfire rubbed her chin in thought. "John, we shall need the bed for this," Starfire finally said. I got up from it and motioned that it was all theirs to use. "Raven, please climb upon the bed, lay upon your back, spread your legs, and prepare for defeat," the smug alien ordered. Sighing, Raven obeyed. Kneeling down in front of her, Starfire traced Raven's labia with her finger. "When does the count down start?" Raven asked, biting her lip.

I smirked. "It did about...twenty seconds ago," I snickered. Starfire pouted. "John, that is unfair!" "You should have asked before. You're running out of time, Star." Starfire lowered her head and started to eat Raven out. Raven groaned, gripping the sheets in an effort not to instinctively play with her tits. I knew this because whenever I screwed her, her hands went to her boobs like clockwork.