Having been holding back all day from touching the man, there was no way Jack was going to initiate further touching unless he had a big green light and a sign pointing to Greg's crotch saying 'Go for it, Big Boy'. He didn't want to ruin what was going, so he was happy to just shift his leg a bit so the man's hips hit it more often.
It was another moment before Jack let out a soft whine and had to pull away for a moment to get some air, panting softly as he looked up at Greg, his smile growing at the sight of the man's lipstick just about everywhere, and knowing he probably looked even worse.