What is the origin of the idiom "get in on the act" and when to use it?

The origin of the idiom "get in on the act" can be traced back to the world of entertainment, particularly in theater and show business. In the context of theatrical performances, an "act" refers to a distinct segment or portion of a play or show, often with its own storyline or performance. The idiom likely emerged from the idea that individuals wanted to be part of the excitement and attention associated with a successful performance or show. It is used to express a desire to become involved in an activity, situation, or opportunity that is already underway and generating interest or success.