When I shook hands the other day with the Dad of one of my kid's friends, I found myself with a palm-full of his fingers.
And I had no idea if he was just a bit slow to prepare the open hand, if he was testing me for freemasonry, or if it was a misguided attempt by a white, middle-aged man to start one of those multi-stage finger-grasping exercises that really should be left to the brothers. (It's like trying to get bowing right if you're not Japanese. You can't.)
I just ignored it. Mind you, it reminded me of one of the jokes of my extended adolescence. You'd tuck in your middle finger when you shook hands firmly, lean toward your acquaintance, and whisper confidentially "Excuse the wart."
The best one of these was to keep shaking hands and not let go until it got seriously embarrassing. (A man is programmed not to pull out of a shake unilaterally -- the ending comes about by one of those inexplicable bits of telepathy that the social psychology department at my alma mater should be researching.) Then you'd say, shaking more firmly and a little more rapidly, "Oh, by the way, I'm from the planet Neptune. We have our sex organs in our hands." Well, it amused us for hours back in Hounslow.