Blackboard
A chalkboard is black when clean and dirty when written on with white chalk.
The answer to the riddle "What is black when it's clean and white when it's dirty?" is a chalkboard. When a chalkboard is clean, it appears black; however, when you write on it with white chalk, it becomes "dirty" and takes on a white appearance.
A blackboard
Blackboard
A blackboard.
A chalkboard ~_~
A chalkboard ~_~
blond, dark, fair, auburn, dirty, clean, black
A chalkboard ~_~
it is dirty
one is clean and the other dirty??