When ya gotsta be legit
Signing legal documents. For example, sign in at a race.
When you can have fun with it
When you can have fun and it is not legaleze.
When I signed my first autograph I actually signed my real name = BORING. I also noticed that person was having fun having their picture taken with a bicycle racer. So I thought: why not have some fun with this? They clearly did not know what I had actually written. And they might look at the signatures after they got home, see Elmer Fudd, and have a good laugh. So I changed to signing autographs as Elmer Fudd. Except in the spring of 1999 when I signed as Dudley Doright, until later that spring when someone told me I was misspelling Dudley Do-Right. So I went back to signing autographs as Elmer Fudd (fewer letters to remember).