Summary: Always Goose Your Geek
The first pat on the ass freaked him out beyond belief. They'd just got back from a highly successful mission on P3X83 where they'd traded farming techniques and hybrid seed for meats and fruit.
Ford and Teyla were already in the jumper bay and Rodney was halfway down the ramp when it happened. The hand was there and gone in a fraction of a picosecond, leaving Rodney open-mouthed and gaping at John's back. The culprit sauntered off as though he hadn't shaken Rodney's world, his 'Good job, guys!' trailing along behind him.
After that, it seemed to become something of a ritual - a ritual focussed solely on his rump, Rodney noted. Neither Ford nor Teyla ever got a swat and Rodney felt absurdly flattered, proud, and somewhat special.
A couple of months of routine hand-to-asscheek confrontations, and then suddenly the squeeze came into play. The feel of John's fingers digging briefly into Rodney's buttock rendered Rodney mute for several minutes. He almost came.
'Routine', after that, became a swat-squeeze combination at the end of every mission, barring medical emergencies.
The fifth combo came complete with a smirk and raised eyebrow and Rodney finally decided that enough was enough. He shadowed his tormentor through the city to his room, and used his foot to stop the door from closing before scooting in.
"Major Sheppard, have you been flirting with me, or is there some new military regulation somewhere that parses out to 'Always Goose Your Geek'?"
John stared for several lengthy seconds and then stepped in close.
"Jeez, McKay, it took you long enough to get a clue!"
The rest of Rodney's quite acerbic, well thought-out attack was silenced by John's tongue in Rodney's mouth.