Joke

Sherlock Holmes's sister, Ella, was a bit confused--not that she suffered from dementia or anything--she simply was a bit "blonde." She was always getting her two twins confused, even though they were fraternal, not identical, and everyone else could easily tell Patricia from Theresa.

One day Sherlock's sister invited the great detective and his assistant to a piano recital that Patsy was to give the following evening. When she left, Sherlock's assistant said, rather bewilderedly, to Sherlock, "I didn't know Patsy was studying the piano." To which Holmes replied,

"Ella meant Terry, my dear Watson."