I guess the first time I overheard girls talking about it was in Junior High. There was a bunch of girls chatting away a few chairs away from me and I saw one of the girls wrapped her index finger and thumb around her wrist and said, "It was as thick as my wrist!" and the other girls giggling. That made me feel insecure because there is no way my penis is as thick as a wrist. Another time was in my first job. There was some older secretaries there and I overheard one of them talking about a Richard Gere movie. She kept saying she was "disappointed" in what she saw. When I got home I looked up the movie section and found out that Richard Gere appeared in a full frontal nude scene. Later on while listening to Howard Stern, I heard him make fun of that scene. So, it seems that size is really important to women based on these personal observations.