What is Stale Green?
1.
a traffic light that has been green for a long while so you know any second it is going to turn yellow so be ready
better get ready to slow down, that's a stale green light
See
2.
When a traffic light in the direction you are going has been green so long that you know it will change any second.
Passenger: "It's a stale green man, you're not going to make it."
Driver: "No way. Look, it changed after we went through."
