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 naked.
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, both deciding
that no harm can come from letting a blind man into the room,
they open the door.
"Nice boobs," says the man, "Where do you want the blinds.
I know a nun joke even filthier than any of those but I don't think I dare tell it. In fact, I know at least two!