There were three nuns, they all told the priest that they were going to do one sin each. So the priest says, "ok, do your sins, come back, and I'll bless you." So, they went to do their sins and came back to get blessed.

The priest asked the first one who was laughing what her sin was. She said, "I had sex with a guy."

The priest said, "ok," blessed her and said, "go drink some holy water." So she did!

The next one was laughing harder, and the priest asked her what her sin was. She said, "I got in a fight with another nun."

The priest said, "ok," blessed her and said, "go drink some holy water." So she did!

The priest asked the last one who was laughing even harder what she did.
And as she was laughing she said, "I pissed in the holy water!"