Of course she doesn't stop.

You squirm more, but she doesn't cease. It stops only to start again, and then stop once more. You turn around to lay on your stomach in hopes to hide your growing arousal, but being put in such a helpless state, wearing nothing but a bathing suit, in front of a whole beach of people, is humiliating. At any time, she could make you cum but no longer switching it off. Trying not to panic, you take deep breaths, and remain face-down on the towel.

"Are you all right?" whispers Alison near your ear. "You're shaking a little bit."

"Hey! How are you ladies doing over here?" comes the voice of Troy. Both him and Roger are walking over.

"Wonderful!" answered Alison immediately. "Just soaking up some sun."

The two young men, dripping wet, stand over you as you remain helpless on your stomach. You let out a meager greeting, but suddenly the vibrations start again. Your eyes widen, and you quickly stare back down at the towel beneath you with a hand over your mouth. This time, it brings you dangerously close to the point of no return. In desperation, you look to Alison, and see the widest smile you've ever seen. Behind her back, she switches it back off.

"We should take a dip in the water too, Jane," suggests Alison.

You shake your head. Out there, you'd be even more exposed.

"We can just chill here and chat," Roger says. "No worries."

You carefully roll your body around, and notice Alison staring at your legs. She gives you a wink. When you look, you see the front of your bottoms to be noticeably damp. In panic, you put your hands between your legs. Roger and Troy are directly beside you. What would they say if they saw you in this state? You haven't touched the water yet, so why would you be wet?

Against your own will, you actually respond that going into the water does sound nice, and that you'd like to get in there pretty quickly!