Let's go at this from a different, a little less risky, angle (and I don't mean with the fucking).

While you decide that calling out to Farrah would probably be the wrong thing to do, you know you can't give up entirely on the idea of getting to fuck both of these hot sisters together. So you decide to take a chance, though maybe less of a chance than calling out to her would be, and lean in so that you can whisper to Teesha. This also has the added effect of changing the angle at which you thrust into her, making you reach that much deeper inside of her as she angles her hips to accommodate your movements and moans throatily for you.

"Hey, sweetheart...", you whisper to her, your lips brushing against her ear and your breath falling hot and moist upon her skin, "Don't look now...but I think we got an audience here."

At your words, one of Teesha's four eyes glances to you questioningly. You jerk your head subtly towards the doorway, a difficult task as you're still in the middle of driving your cock inside of Teesha's tight pussy while you do it, and Teesha's gaze moves over there. You see her eyes widen slightly as she sees her sister there pleasuring herself while watching the two of you and you think, for a moment, that she might just react badly to the sight. You are relieved, however, as you see a slow, sultry smile spread upon her lips instead and all four of her eyes move to focus on you as she leans close to whisper back to you.

"Looks like she's liking the show...so why don't we give her a better view?", she says and, suddenly, she shifts her body so that the pair of you are rolling over so it is now you laying on your back on the table while she lays atop you, her firm breasts pressed tightly against your chest and her flat belly sliding against your own.

She doesn't stay in that recumbent pose for long, however, as, after giving you a light kiss on the lips and a pair of winks, she rises up so that she is straddling your hips with her knees braced on either side of you. She lifts her hands up to drag along her skin, giving you a show of her caressing her stomach and then her breasts as she looks down at you. Slowly, so very slowly, you feel her lift herself up along your rigid cock, her knees flexing as she lifts herself up along your length.

As she does so, you glance towards the doorway and you can see Farrah's eyes glued to the sight of her sister sliding up along your thick prick, a sight she now has an unimpeded view to in the new position Teesha has taken. You realize now what the Phyrellian meant about giving her sister a better view as, before, all Farrah could really see was Teesha's legs wrapped about your waist and your ass flexing and moving as you thrust inside of Teesha. Now, though, well, now she was getting a full view of her sister being fucked by your hard cock and it seemed she quite liked that view as her fingers pinched her nipple hard and her other hand started to work even more furiously in her panties.

You chuckle deviously at that as you look to Teesha, your eyes meeting hers as you share a lustful sort of amusement at Farrah's arousal at your actions. Of course, your eyes end up shutting tight in pleasure as Teesha slides herself back down along your cock at that torturously slow pace until you are hilted within her again. She rolls her hips as she grinds against your groin, your cock shifting and moving inside of her with her movements, and you have to moan as your head falls back onto the table with a thump.

"Fuck, Teesha. You really know what the fuck you're doin', don'tcha?", you murmur heatedly before reaching out to grasp her hips tightly and giving her a wolf's grin, "Well, so do I."

With that, you roll your hips to shallowly thrust yourself into Teesha's pussy, grinding your pelvis against her clit and making her gasp as you do. She shudders in sensation as her hands find her breasts to tease and pinch her nipples while you thrust up into her, a movement she facilitates by starting to lift and drop herself upon your cock in time with your hip's movements. Soon enough, you're fucking each other hard on the table, Teesha bouncing on your cock quickly and you thrusting up into her eagerly.

All the while, Farrah watches and, between thrusts and moments of blinding pleasure, you glance over at her to see that she's let the top of her jumpsuit fall completely so that she's stripped to the waist as she pleasures herself. She is half-naked and gasping in pleasure as she watches you and you are just about to call out to her to say she should come over here and you'll take care of that for her, but you're beaten to the punch. It seems you weren't the only one who remembered Farrah being there as Teesha suddenly turns on your cock so that she's riding you reverse cowgirl style, her tight little ass facing you and the slender line of her back arched as she now faces the doorway.

You can't see her face, but you imagine she's smiling with lust in her face as she stretches her hand out towards her sister and beckons her with a finger. "You know, it's impolite to peep, sister dear.", she says with a heated chuckle that changes into a moan as you grasp her tight ass and grind your cock up into her, "Now...why don't you come over here...so you can share some fun...with your little sister. I'm sure Derrick here...won't mind."

"Fuckin' A, I won't mind!", you call out in agreement, causing Teesha to chuckle again, one of her hands coming down to slap you lightly on the thigh in mock admonishment for your outburst.

Farrah, meanwhile, seems shocked to have been discovered and then seems uncertain of what to do as she ponders the invitation she's just been given, certainly wrestling with her own lust and her own issues with casual sex as a whole.