back in the gap 

back in the day, a long period of time previous to the present

me and that ole' boy used to chill back in the gap

back in the gap by THCrandomhero October 18, 2006

Back in the gap 

When a railroad conductor goes in between two train cars.

“Job 825 conductor going back in the gap”, “Engineer understands conductor is back in the gap.”

Back in the gap by Legendary Engineer Q August 19, 2025