"Yanking My Chain" Gold rush days in the US. Being in a mine the toilet was a modified mine cart with a hole cut in the top to "go" in. You'd climb on top of the cart, pants around your ankles to "go" and someone would give the cart a good hard push and off you'd go through the mine on top of the cart pants around your ankles screaming though the darkness. So to stop that you'd carry a piece of chain with you, wrap it around the wheel to act as a chock so you wouldn't go for a ride. So when you'd hear someone "YANKING YOUR CHAIN" you'd tell them to stop yanking your chain!

If not you were getting ready to "GO FOR A RIDE"!
