This is a very, very cheesy riddle. If you know Chinese(Simplified) then this shouldn’t be a extremely hard challenge. If you don’t know Chinese, use a dictionary or Google translate. Here it is:
买有卖有,人人都有
This is how I translates it(I won’t try to trick you with this, this is the actual meaning):
What is something that buying and selling have, but it’s also something that everyone have.
Hint: This riddle does not only have to do with the meaning, you should also look at the word structurally.
Good luck!
Since I know Chinese, the answer is obvious for me. I’m pretty sure the answer is 头, or head.