A common form "what does that have to do with the price of tea in China?", is a retort to an irrelevant suggestion. This facetious usage implies that the topic under discussion might as well be the price of tea in China for all the relevance the speaker's suggestion bears on it.
Suzie: I love my new skirt!
Anne: I know! I love my new shirt!
Beth: Look at this hot guy on my phone!
Suzie: What does that have to do with the price of tea in China?
"What does that have to do with the price of tea in China?" is an expression which denotes that what the other person just said is completely unrelated to the original topic.
Person A: President Bush is the best president EVER!
Person B: No, he's not! He's the worst president!
Person A: Why do you say that?
Person B: Umm, I just bought a guitar.
Person A: Well, what does that have to do with the price of tea in China?
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.
FRIEND A: "Did you just take a stealthie of me?"
FRIEND B (turning phone around): "no I was just using snapchat's new filter, see?"