Why I Punched Tommy Lee ...
Rock told the judge that he and Lee had bad blood over their relationships with Pam Anderson.
Rock claims before the VMAs, they had exchanged some cell phone smack talk -- but somehow ended up next to each other during the VMAs.
Rock told the judge that Lee tried to sit down next to him ... so Rock smacked Lee's hat off and popped him in the face.
However, Rock also claims that Lee called him after the incident to apologize ... and testified the two are now friends.
UPDATE: Check out part of Rock's testimony above -- when he first sat down, he had to acknowledge that he also goes by the names "Devil without a Cause" and "Kid Rock and Roll Jesus."