Ridgie Jumping 

Breaking into the guard carriage of an old Australian NSW suburban train and jumping off the back of the train into the train tunnels. The train is generally a C-set or a K-set.

John: Hey man, feel like doing some urbex
Sam: yeah ok sounds good
John: let's do a ridgie jump
Sam: Yeah man, ridgie jumping sounds good, I haven't been in the train tunnels for a while, let's do it!

Ridgie Jumping by Urbex4life December 3, 2020

stump jumping ridge runner 

This term is used as a derogatory way to refer to back woods, hill billy, red neck types of guys.

Here comes Joe fresh off the mountain. Him and his old pickup truck covered with mud. He is the worst stump jumping ridge runner I ever saw.

stump jumping ridge runner by old geezer May 6, 2011