I don't think Sherlock Holmes actually ever says that. I can't say that unequivocally because I haven't read all the Sherlock Homes stories but I have read two so far. Why? Because as I mentioned in A Love/Hate Relationship - My Kindle, you can download classic books to your Kindle for free. I downloaded the first two, A Study in Scarlet and The Sign of the Four and read them over the last few weeks, and I have to say while no "Elementary Dear Watson" has been uttered, I have enjoyed them both, much more than I thought I would.
If you're a fan of the mystery genre, it really isn't too old school to go back to the some of the originals - if you have a Kindle (or a good local library) and can read them for free - why not!