This one of my dad's favorite jokes:

A young preacher in the seminary had a real problem with remembering names from the Bible. He was always getting them confused and couldn't tell Melchisedec from Methuselah. One week, he had the chance to preach for a vacationing pastor. He was so worried about the requested subject of his sermon, the three Hebrew boys in the fiery furnace, that he went to one of his professors about what to do.

"It's simple, my boy," said the professor. "Just take a small card and write down Shadrac, Meshac and Abednego on the card. Then fold over the top inch of the card and put that in the inside breast pocket of your suit coat. If you get flustered, just open your coat and glance at the card. You'll be fine."

So the young man did as his professor said and was thrilled. He even practiced with it a few times. Sunday came and he checked his pocket and made sure the card was there all during the song service. When it came time to greet everyone just before the offering, he came down off the rostrum and shook a few hands on the aisle. Unawares to him, the card fell out.

He got the nod to start his sermon and he jumped right in. He was going great for a few minutes then said, "And who could forget the names of those three Hebrew boys in the fiery furnace?" And he looked inside his coat and read aloud, "Hart, Shaffner and Marx!"