大学生被卖苗疆养蛊人:What is black when it`s chean and white when it`s dirty?

What is clean when it is black and dirty when it is white? What is black when it is clean and white when it is dirty? What is black when it is clean and white when it is dirty? Riddles(What is black when it is clean and white when it is dirty?) What is black when it is clean white when it is dirty? What is black when it isclean and white when it is dirty? What is black when it`s chean and white when it`s dirty? what is black angel what is the black hole is? what is mean by black lllie