You and Emma start to make out.

You take Emma by the shoulder and pull her in for a kiss. Not just the pleasant little peck one offers in polite company, but really locking lips and swapping spit. A public display of affection like this would make any witness jealous, but in front of your parents and Sophia, it's downright nasty. You take a big handful of Emma's shiny, slippery tits as you feel her tongue fight with yours. You and Emma thrust against each other, bodies rubbing top to bottom. It goes without saying that you've already got a hand stroking her pussy beneath the boiling water. Emma doesn't keep it to herself.

"Mmmm, John, you know just what my pussy wants."

That does the trick. Your Mom glides across the hot tub to embrace Emma's Dad and give him an adulterous smooch, which Emma's Mom watches with relish. A moment later, she's sitting in your Dad's lap, wiggling her butt and letting him suck her juicy mature melons. The sound of humans finding sexual relief starts to build up around you, hisses and rumblings from impulses rapturously obeyed. You keep Frenching Emma only to find another tongue entering the fray, and you pull back to see Sophia is worming her way into Emma's mouth.

"Do you remember the surprise I told you about in the car?" Emma asks, and Sophia nods in anticipation. Your girlfriend looks over at you.

"John, stand up and show Sophia your surprise." You dutifully obey, savoring the look on Sophia's face when she sees your full erect length emerge from the water.

"Oh my God!" Sophia practically gasps. "That's what you've been fucking? No wonder you're so horny all the time!"