Stephy was confused about the "shame on you" finger gesture (a.k.a. "the forefinger rub") that I occasionally do to her when she's a naughty baby.
She thought it looked like grating cheese ~ and I've always thought of it as whittling a stick.
Finally, I felt compelled to google it, and came up with this:
"Dr. Givens, Prof. Becker came up with a question about a finger-on-finger gesture (both index fingers extended with the others clenched, and one rubbing on the other, in a sort of whittling motion) that is universally (at least in the U.S.) understood to be a "shame on you" gesture used by or with children. The question is: Where did the gesture come from? Does it symbolize something? Related questions are: How universal is it outside the U.S.? Is it primarily a part of children's culture? I enjoyed looking at the Nonverbal Dictionary, but
could not find such a gesture. We would appreciate any answers to our questions. We have gotten a number of the Physics faculty here wondering about the gesture (and perhaps wondering how two astronomers came up with such questions)."
--Glen W. Erickson, Physics Professor
Emeritus, University of California, Davis
Yes, according to Desmond Morris (1994:94-5), the gesture (forefingers rub) means "shame," and is restricted to North America. The rubbing of the two forefingers is thought to symbolize friction. There's a related gesture (forefingers scrape) from Wales, Germany, and Austria, in which one finger "saws" across the pointed other one. The latter is considered an insult, again with the friction message coming though.
The origin of both of these gestures is unknown. The closest sign in The Nonverbal Dictionary is the entry for "Point." In the forefinger rub, the scraped digit may be pointed at the guilty party."
In parts of Mexico rubbing one index finger across the other is considered obscene.
A World of Gestures
Members of a culture typically know ONLY the gestures from their
own society. For example, Americans know gestures for messages
such as "OK", "Shame on You", and "Crazy", but are tend to be
ignorant about gestures from all other societies.