Arthur doesn't know how literal that innuendo was, and at this point he's too afraid to ask.

If he weren't already sitting down, he feels like Crichton's moan would take him out at the knees. He laughs under his breath, and then says into Crichton's skin, in a voice that's had the bottom fall out of it: "Well. You've doomed yourself to a lot more of that."

How about more nibbling, and a thumbnail drawn carefully up the inside of Crichton's thigh, followed by lighter fingertips, something Arthur can hardly comprehend himself doing despite the evidence right in front of him. He knows in broad strokes what this is leading to, but he's so much more compelled by every moment, movement and sound leading up to it, and it keeps fading out of view, like something huge under the water.

...not to spoil the mood, but: "Did, er... did- did we lock the door?"