你去忙吧 is a Chinese saying that means "you go and do your thing" or "you go and take care of your business." This phrase is typically used to encourage someone to go and do what they need to do, or to politely tell someone to leave and let you do something.

I'm not sure about the exact origin of this phrase, but it is commonly used in Chinese culture.

Here are some examples of this phrase in use:

你去忙吧，我这里没事了。 (You go and take care of your business, I'm fine here.)

你去忙吧，我会守着这里的。 (You go and do what you need to do, I'll stay here and keep watch.)

你去忙吧，我会给你打电话的。 (You go and take care of your business, I'll call you later.)