Kim sends Big Willy in to rescue you

By: Cheese111

"But we can't play with him if he's stuck in there." Becky lamented. She started to reach down, wanting to fish you out with a finger, when Kim stopped her.

"Are you sure about that? Because from where I am we've got poor little Willy lost in a cave and I think I know just the way to rescue him." She stood up, pointing her erection at Becky. It throbbed a little with anticipation. Your girlfriend didn't need long to return the gleeful grin, understanding exactly where this was going. But before Kim acted on her idea she kneeled down and spoke to you.

"You hear that, little Willy? Help is on the way. Just hold on tight." She struggled to keep a straight face. It must look kinda silly for her to seemingly be talking to someone's vagina. Becky emphasized the 'tight' by squeezing her inner walls around you, further cementing that you would be stuck in here until they let you out. And given that it was your sister that would mount this rescue, you already knew how this was going to play out.

Becky fidgeted nervously as Kim got up and brought herself closer. She was aware of your sister's extra asset, but she never thought she would be experiencing it so intimately. It's so big. With some trepidation she mumbles to Kim. "Just take it slow, please."

"Of course. Big Willy is a gentle lover." She replied. Becky rolled her eyes at the cheesy line, but soon she was overwhelmed by the sensation of the broad tip looking to enter. It felt like pushing a tennis ball into a garden hose, the lower lips barely able to stretch wide enough to fit the girthy intruder. You could hear the loud, wet squelch it made from up close, watching the narrow opening be filled utterly with the immense head of your sister's dick. It pushed aside the walls, giving you the freedom to move, but there was nowhere to go but deeper. You tried to stay ahead, but between the size difference and the uneven squishy floor Kim was much faster than you. The spongy mass slammed into your back, pushing you into the soft flesh of Becky's pussy whilst it kept going. The yielding mass around you helped mitigate the pressure of that enormous cock steamrolling you.

"Oh, I think I can feel him." Kim cheered, pulling back a little and going in again. She felt the tiny lump that was her brother being squished by her cock. Becky just moaned, having her pussy filled more thoroughly than ever before. Kim was barely past the halfway mark when she hit the cervix, Becky giving a pained moan. Your sister withdrew again, letting you get up just in time to see the twitching slit stop.

"Oh f~" You stopped yourself and held your breath as a firehose of cum blasted you in the chest. Thick goop splattered all over you, drenching you once again in your sister's cum. This was the third cum bath in an hour, how was she able to make this much? The tunnel began to fill up, but mercifully the powerful stream stopped before the level got past your knees. It was scary and overwhelming, but not nearly as much as what Kim said next.

"Alright, little brother. If you want out you best grab hold of Big Willy real good. Because I think this cave is gonna collapse after the flood that just came in." She announced, waiting for the tiny man to make his move.

You slogged forward towards the imposing cockhead. It was a little wider than you were tall and it was the only thing forcing the pulsing walls around you open enough to approach it. You had to get on or you'd spend the next who knows how long in here. And after all the cum that got deposited by her orgasm, you weren't sure if there'd be any air left with you. You threw your arms onto the bulbous tip, but there was no grip. It was covered in slimy residue. Soon it became clear that the only way for Big Willy to 'hold' you would be the gaping slit.

"For fuck's sake." You grumbled to yourself as you got down on your back and pushed your legs in. At the very least you wouldn't go in there head-first, but it was little comfort. You felt the narrow tube take hold of your legs, pulling them in a little until your waist was secured. Suddenly the walls began to move as Kim withdrew her cock from Becky's pussy. They both moaned as it left with a small, wet pop, cum leaking from your girlfriend's pussy. You'd been **** to become part of a twisted threesome with your sister of all people. And you knew that this was just the beginning.