A young boy is standing on a street corner swatting flies. Every time he sees a fly he utters, "fucking flies, fucking flies." Just as the boy says it a shocked priest walks up and says, "You should not curse the flies because every one of God's creations has a purpose."
The little boy, unmoved by the priest's objection says, "bullshit."
"Well tell me 3 things on this earth that God has made without a cause" says the priest. The boy looks at him with a grin and replies, "Tits on a nun, balls on a priest, and these fucking flies."