What's that got to do with the price of tea in China?

Meaning

A colorful way to point out that someone is speaking nonsense or bringing up irrelevant details. It dismisses a non-sequitur by highlighting how far afield the logic has wandered.

Sassy, dismissive

Used in a sentence

• I was complaining about my car payment and he started talking about the lunar cycle, so I asked, what's that got to do with the price of tea in China?
• During the budget meeting, Brenda started describing her cat's diet, and the CEO asked, what's that got to do with the price of tea in China?
• He went off on a tangent about lawn care when we were discussing dinner plans, leading me to ask, what's that got to do with the price of tea in China?