“Would you go to the dance with me?”
“Not for all the tea in China!”

This is a colorful way to say “no”, “absolutely not” or “never”. Tea originally came from China, so naturally it would have the most tea. At one time, tea was unusual and rare in the rest of the world, so it would have been very valuable. “All the tea in China” is worth a lot of money, but still not enough to make us agree to do something we really don’t want to.