Invite them over

"So, Charlie," you begin, "I'm thinking, since you two are having such fun, and we're having such fun--"

"Oh, God," Charlie starts to moan, dropping the phone again. You hear it hit the floor this time with a thud, stopping you in mid invitation.

"Oh, yeah!" Marie says, "Go ahead, baby."

"Oh, God!" Charlie shouts again.

You can hear their bodies slapping together, faster and faster, Charlie's moans getting more frequent and louder until he screams, "Oh...MY...GOD!!"

The slapping sounds stop then. And Charlie's moans taper off.
You glance down at your wife, who smiles up at you, stroking your cock with one hand.

A second later, the phone clunks again as someone noisily picks it up and Marie says, between pants, "Hello?"

"Marie?"

"Oh, Hello Roger. I was concerned you were Charlie's boss." She sounds relieved.

"Listen, Claire and I were just wondering, if your play time isn't over yet that is, if the two of you would like to come over here?"

"Ohh, that sounds fun," she says, then lowers the phone and asks Charlie what he thinks.

"Charlie's still not quite with it, but I'm sure he'll be happy to come. Should we bring anything?"