A staple Old Folk agressive move. Shaking the fist lets people know they are disgruntled but haven't the means to kick your ass. Directly related to the wave off, the fist shake is a time honored right for senior citizens, and adored by the young.
When I burned out in front of Old Man Stephens house, he gave me such a fist shaking that I thought he was gonna bust a jugular.
by Sir Captain of Wynn Bay May 04, 2005