I was driving behind a Chevy Cavalier recently that had the sun roof opened.
Every once in a while, the drivers right arm would twitch upward, toward the sun roof.
I was curious.
Maybe he had a nervous tic or a rare movement disorder called hemiballismus (spasms in one side of the body)?
I decided to pull up along side the driver in the other lane.
Nothing exciting was seen...just the driver periodically thrusting his right arm upward and out the sun roof to flick the ash off his cigarette!