Mike suggested a game of "Greyhound" instead.

I'm sure that even though Emily and Haley were identical twins, genetic clones of each other, they each had their own unique quirks to their self-identities, but the four of us knew Bill and I weren't fucking the twins for their amazing personalities. Haley's pussy around my cock was going to feel just as good as Emily's so I was going to dismiss Bill's suggestion of swapping sisters but the girls liked the idea.

"How about we play a game of 'Greyhound' instead of switching rooms?" I proposed.

"I'm okay with that!" Bill grinned. "Which room though?"

"We'll meet in the middle on the side-by-side berth beds!" I chuckled.

"What's 'Greyhound'?" both sisters asked as Bill and I led them into the tight confines of the side room and motioned for them to get on all fours on the beds.

"It's a game Bill and I made up," I explained. "We have to make our partner cum as many times as possible without cumming ourselves."

"We love that!" the twins giggled.

"But you girls have to try to make us cum as soon as possible," Bill added.

"Why do you call it 'Greyhound'?" Haley wondered.

"Because we fuck you doggy-style while racing to make you cum as fast and often as possible!" Bill laughed.

"I love this game!" Emily smiled.

"There are no losers in this game!" I grinned and knelt behind one of the girls -- without seeing if her pussy was bald or had a landing strip I wasn't a 100% sure which twin I was about to fuck.

"Ready?" Bill asked, placing his large hands on the other girl's upturn ass.

"Yes!" the rest of us cheered.

"Okay, on the count of three..." Bill announced, aligning the tip of his cock against the drenched pussy in front of him. "Three!"

"Two!" I yelled.

"FUCK!" we all screamed.