Here's how it works:
* Organ stops: These are levers or buttons on an organ that control the flow of air to different sets of pipes.
* Pulling out a stop: When you pull out a stop, it activates a specific set of pipes, adding a particular sound to the overall organ's sound.
* "All the stops": To "pull out all the stops" means to activate every single stop on the organ, creating the fullest, loudest, and most impressive sound possible.
Therefore, the phrase metaphorically means to use every resource and effort available to achieve a goal or to make a maximum effort.
It's often used in situations where someone is trying to do their best or to make something as successful as possible.
Example:
* "We're going to pull out all the stops for this event to make it a huge success."