Did you really have to create a thread just to ask that? That's called bitcoin's go to the moon but that phrase is subjective. What's considered as a huge price increase to you might not be to me.
Bitcoin's price goes to the moon mean that the price of bitcoin will increase a lot. A lot of people say that phrase because it's easier to understand. When you said "moon", first thing comes to mind is something "high" or above the sky. Essentially, there's no limit on the price of bitcoin and even we're already at 10k$, you can still say that bitcoin is going to the moon (meaning price increase).