What did Sherlock Holmes keep in the toe of a Persian slipper?

This is a trick question! Sherlock Holmes didn't keep anything in the toe of a Persian slipper. This is a common misconception that has been circulating for a long time, likely due to a misunderstanding of a specific scene in the stories.

In the story "The Adventure of the Blue Carbuncle", Holmes mentions using a Persian slipper as a hiding place for the stolen jewel, but he doesn't actually keep anything in the toe of it. The slipper is only used to demonstrate the potential hiding places for the stolen gem.

So, while the image of a Persian slipper with hidden treasures might be fun to imagine, it's not a real part of the Sherlock Holmes canon.