You fuck Lydia, then John calls

Lydia kneels on all fours in front of you, her phone in one hand, and looks back at you. Shes still wearing her dress, but its short enough to leave her ass and pussy completely exposed in this position. "Lets give that slut Hailey a show. Fuck me!"
For a second you´re tempted to give her your real cock, but you decide otherwise and align the strap-on with her pussy, so that your real cock lays on top of her ass.
You can see Lydia texting John again.

Lydia--Hes entering me now...hes so fucking big

John--the dildo??

Lydia--yeah, sure, thats what i meant---the dildo

Then you push your hips forward, and the strap-on into Lydia.
"Oh fuck!", she cries out. "Yes! Stretch me out!"
Shes a bit theatralic, but you realize that she wants to give Hailey a good show. Then, suddenly, her phone rings.
"Its John! Oh, this is perfect."
She answers, putting the phone on speaker, while you push in further.
"Hi Babe...ah fuck...whats up? Im kinda in the middle of something."
You hear John respond: "I went to the bathroom real quick, I needed some privacy, your messages made me horny...Wait, are you really masturbating?"

"Well of course", Lydia pants, while you begin to slowly move. "Although "Getting fucked" is a bit more fitting...babe hes so big!"

"Ethan?", John asks, clearly thinking that she was just roleplaying, and you were not actually there, "Yeah...he is pretty big, isnt he?"

"So much bigger than you...fuck...Ethan, continue, dont stop!"
You realize you stopped moving while listening to their conversation, and quickly begin to fuck her again.

John seems to listen to his girlfriends moans for a second, then he says: "Can you describe whats happenign over at yours?"

Lydia smiles, then, interrupted by her moans, she responds. "Well, I asked Ethan if he wanted to stay a bit longer after dinner, and he was more than happy to. To be honest I think he saw that i was wearing no underwear. And well, one thing let to another..."

"Continue", John says, breathing heavily.

"I bet you wish you could jerk off right now. In the bathroom of the restaurant, while listening to your girlfriend having sex with another man right now. You´re so pathetic. Well, I guess I´ll do you the favor. When we got to my room we layed down on the bed, but I was to horny, I couldnt help it, seeing his big, hard cock pressing against his trousers. And now, before I know what happened, hes behind me, I´m on all fours, and hes fucking me, making me his bitch. FUCK!"

Lydia interrupts herself, you pushed deeper, then you continue, even harder.
"You like what you hear babe? Like hearing about your slut girlfriend?"

After a couple moments of silent, he responds. "Yes."

"Do you think about how we look right now? Ethan behind me, towering over me, and me, your girlfriend, in front of him, completely submitting to his massive cock. OH MY GOD! Fuck....hes so deep...I dont know how much longer I can last."

Then she looks back at you: "Harder Ethan! Fuck me, stretch me out, so deep, while my loser boyfriend listens! YEs! Keep going! Fuck this cheating slut! Fill me! Make me cum on your cock! FUCK...Ethan, I´m....."

And, with her whole body whaking, she cums on the stra on. You watch her squirm as she cries out in an orgasm which people down on the street could probably hear.
"Babe, I gotta go", she says, her voice shaking, "Ethan still needs to get off, and I´m going to offer him my body to do whatever he pleases."
Then, without waiting for a response, she hangs up.