The word "Jocko" was commonly used on the London, Midland and Scottish Railway to refer to their 3F 0-6-0T shunting engines. A more common term used for them is "Jinty".
a straight jock who is so straight and so jock-like that he's obviously a neandertal and/or gay. Almost always from the suburbs.(Thus it is practically a synonym for "male suburbanite")
Yo, look who's cruising down the main drag in their white Jeep on a Friday night lookin' to get some- it's species jocko homo!