The writing on a thespians baseball cap
"JAFO" was written in large letters on Daniel Stern' s character's baseball cap in the 1983 movie Blue Thunder. It was given to him by his colleagues on his first day of work as Roy Scheider's chopper co-pilot/observer and is supposed to mean "Just another fucking observer".
The meaning of the acronym was changed for the same titled TV-series, where it meant "Just another funny observer" and is being worn by Dana Carvey.
Source:
http://www.jumptheshark.com/b/bluethunder.htm