Perhaps Ralph is a really nice guy, and it was a delayed reaction to something that happened directly preceeding the handshake.
A bad thing happens (Ralph is disgusted)
Enter 14 year old, Shake.
Exit 14 year old.
"WTF" delayed reaction.
He just was a little too quick on the draw, so he was still looking at the nice young man who shook his hand.
Kind of like the time I hit my sister in the can with a dart. I started throwing the dart, she asked me a question during the release, I turned to acknowledge her, and boom, dart in the a$$. To this day I am still percieved as a jerk for this incident, but I swear it was an accident.
Extenuating circumstances man!!!!!!!!!!!!!