In case you were wondering what goes on back there.

Back in the early days of bowling, people would be hired to set up the pins after you knocked them down. As players were often drunk and just hurling the balls down the lanes, this could be a pretty dangerous affair, as there was a significant chance you would be hit by an errant pin.

Now, this system is significantly less dangerous — and, honestly, pretty mesmerizing to watch. Here’s an animation of how it works behind the scenes, plus a real-life example of one of these machines in action: