In medieval times, priests sold pieces of heaven to people for a hundred coins, and people bought them.
A wise man was frustrated that people were buying them so he found a solution.
He went to a priest and asked, "How much is all of hell?
The priest looked surprised and asked, "Hell?"
"Yes," he said.
The priest without hesitation said: "Fifty coins."
The man gave him the coins and took the certificate.
He went and put it in town square, and said: "I have bought all of hell and I won't let any of you in."
This man was Martin Luther.