Protesters formed 'a human chain' [=they stood next to each other with their arms linked] around the ancient tree to prevent it from being cut down.
In the United States, the President as the commander in chief is at the head of the military 'chain of command'.
I thought he really won the lottery but he was only 'pulling my chain'. [=he was only playing a joke on me]
(..) you only have to fire once. That's how Dad did it. That's how America does it. And it's worked out pretty well so far. Find an excuse to let one of these off the chain, and I personally guarantee you the bad guys won't even want to come out of their caves. For your consideration, the Jericho. (..)2008 Iron Man