A hasty one.

Rob starts typing. He forces himself to not think about it twice. Aileen's presence, her position on top of him and her hands rubbing his chest certainly help him to focus on what he wants right now, instead of what could happen afterwards.
Afraid to loose the spark of insanity and lust that has come over him, he quickly types a rule, keeping it as short as possible:

8. Consentual public sex is accepted.

"Here goes nothing. If it's bad, at least it'll only go uphill from there." he whispers to himself as he presses enter.
Afraid to see what the app would make of the rule, he turns off the phone screen as soon as he sees the green light flash at the top right corner of his phone.

He feels Aileen shudder. When he looks up at her and she opens her eyes again, she has a knowing smile on her face.
"Finally, there we go!" She kisses him, before adding: "We're both still here, the world didn't implode."
Rob nervously chuckles, but kisses her back. "Don't tell me the result. I don't want to think." He whispers.
She nods and let's her hands wander under his shirt. "Then let's not. Just you and me. Let's forget everything else."

That's enough for Rob. He pulls off his shirt and throws it to the ground.
Aileen uses their momentary seperation to jump to her feet and swiftly pull off her shorts.

The two of them are on top of each other again as quickly as they took off their clothes.
Aileen is once again on Rob's lap, fruitlessly fiddling with his belt. Rob's hands have found their way under the seam of Aileen's loose shirt.
He teases her nipples as they lustfully continue their make-out-session.
Finally, Aileen manages to open Rob's belt. The two separate again, both heavily breathing.
Rob pulls down his pants, while Aileen puts his shirt onto the bench as a make shift blanket.
He sits down again, his dick almost painfully hard. He grabs Aileens wrist and pulls her towards him.
His urgency is focused, as if he was trying not to think about what they are doing. Aileen smiles as she let's herself be pulled back onto him.
The butterflies she feels within her stomach flutter even wilder at his demanding presence.
She's kneeling on the bench now, with Rob between her legs. He grabs her ass and kisses her stomach, looking up. Aileen grabs at her own tits through her shirt.
"Please.." she whispers.
Rob pulls her waist downwards, an invitation that Aileen gladly follows.
She lowers herself. She feels the heat of Rob's dick against herself as she rubs against it a few times. She wants him to initiate. She wants him to take her.
"Fuck.." his exclamation is whispered and out of breath. He aligns himself with her entrance and pushes her down. It's not an invitation this time. It's a demand.
One that Aileen once again follows with lust in her eyes.

As he glides into her, their lips meet once more.
Finally, Rob feels the pressure of the world around him disappear. The possibility of being caught, the shame of being nude in public, the pressure of society finally vanish around him. There's only Aileen, himself and the lustful passion he feels right now that overpowers all other feelings.

Aileen begins to move up and down. Rob tries to assist by lifting some of her weight at her waist.
It takes them a moment to find their rythm in this unfamiliar position and environment, but as they hear each other's muffled moans grow stronger, they abandon expectation and focus on what feels good. Rob thrusts upwards while Aileen hovers slightly, grinding her hips.
They have yet to break their kiss, even as both their lips start to redden from the intensity.
Rob's grunts become more intense. Aileen breaks the kiss to come up for air.
She throws her head back, with her eyes still closed. She doesn't care about being loud anymore. Her moans further stoke Rob.
His lips find a new target as he pushes her shirt up and teases her nipples.
He feels himself approach an orgasm and his thrusts become more urgent. He tries to calm himself.
"one.... two... thr-...fo-" Aileen can't help but smile as he hears his moans trying to form words. She takes it as a challenge.

She leans down, grabbing his face, bringing it up to hers to kiss him. She feels how his body tightens as he quickly approaches his orgasm.

"You there, Lovebirds! EXCUSE ME! I'm afraid you can't do that here!" A rough, loud voice startles the two and immediately shocks them out of their own private universe, back into reality.