Like this one!

Two nuns are ordered to paint a room in the convent, and the last instruction of the Mother Superior is that they must not get even a drop of paint on their habits. After conferring about this for a while, the two nuns decide to lock the door of the room, strip off their habits, and paint in the nude.

In the middle of the project, there comes a knock at the door. "Who is it?", calls one of the nuns. "Blind man," replies a voice from the other side of the door. The two nuns look at each other and shrug, and, deciding that no harm can come from letting a blind man into the room, they open the door.

"Nice tits," says the man, "where do you want these blinds?"