In the epilogue of Scourged (Iron Druid Chronicles), a main character receives a letter that's written in red ink. The deliverer of the letter indicated that the sender had hoped the receiver would get the joke. What was the joke?
“Jesus wrote me a letter?”
“Yes, I thought it was a bit eccentric, for we haven’t so much as a book of stamps in heaven, never mind a postal service, but he likes to keep us guessing, you know.” She held out the letter to me and I took it.
“And also with you, Mary.” I looked at the envelope, which bore my name on it without an address. “Ha! He wrote it in red ink?”
Mary tittered. “He thought it was funny and said you might appreciate the joke.”