Super old thread but back in 2010, I definitely had this happen to me.
I had a male friend who was dating another friend of mine (female). I was over at his house for his birthday. When I was leaving and went to go shake his hand, he took his index finger and scratched my palm. It was clear that this was a come on, but it took me a while to process it.
I would never have done anything to come between my friends, and even if they weren't together, it would have made things pretty awkward. They're married now, have a kid, and time has gotten the better of him looks-wise but he was definitely hot back then.
Coincidentally, I did see his dick through the peephole of his boxers one time, so I had some material to fantasize with.