I'm assuming you are talking about things like sharing amongst friends, but I can't find any evidence that is actually covered by fair use.

purposes such as criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research, is not an infringement of copyright. --Wikipedia, "Fair use"

Certainly you won't get sued for sharing your Metallica record with your friend Bobby, but I don't believe that is related of fair use.