So the decorator hands the painter a can of mauve paint and tells him, "Here, put some of this in that can and mix it."
The painter pours some of the mauve in the can of white paint, and mixes them with a stirrer.
First he stirs the paint about ten times clockwise, then he reverses the direction of stirring.
The decorator sees him do this, and yells, "What are you doing??"
"I'm mixing the paint" The painter says.
"Why are you going the opposite direction now?" asks the blonde, pointing to the mixing stick, "Don't you know that you'll unmix the paint?"