Clearly the only right answer is "physical touch" or "words of affirmation" *grins*

I think #2 for both, actually. Rodney's a busy guy; if he's giving up time that could be better spent in his lab to hang with you, he clearly likes you. And John's just not a people person, though he's good at faking it. If he wants to spend time with you, it's a big deal.