My sister-in-law Carol is Korean. At a family gathering, Carol said that she didn't understand why all of my mother's houseplants did so well and all of hers died. I told her that my mother had a "green thumb" but she had a "yellow thumb".
Everybody laughed. Humor is sometimes not easily translatable from one culture to another. Carol asked me to explain and I told her that in the United States if someone were good at raising plants then we said that they had a "green thumb". Carol looked at her thumb and said, "Oh, I get it--mine don't grow--I have a yellow thumb--oh, it's funny--I laugh!"