Here's a groaner:
Jesus and the Apostles were together, and there was a crowd with them. Jesus spoke:
"-y = x2 - 3x + 5",
then fell silent again.
There was a stirring of the crowd, who appeared puzzled. One of the crowd leaned over to an apostle and asked "what does this mean?"
The apostle replied, "Sounds like another one of Jesus' parabolas."