When a well-endowed man stands with his hands on his hips and shakes them forward and back, his penis provides an example of a pendellum. His "head" will swing back and hit the top of his butt crack and swing forward and hit him in his abdominal muscles. Probably named after a man named Fiegle and the term is commonly used on the East US coast.
by Noisewater May 3, 2006