In the sixteenth century a papal bull or bulla was a decree from the Roman Catholic Pope.
It was sealed with a stamp bearing the likeness of St. Peter accompanied by the cock that crowed three times before the crucifixion.
After the reformation, Martin Luther issued bulls of his own that contradicted the Vatican.
His followers considered papal decrees as lies and referred to them from their seals as “cock and bull.”
Something we consider untrue is called a “cock and bull” story.
