The code is

that's Benedict Cumberbatch's birthday...

I love this!

My bday is July 19th :D

Lov it !

This is easy, you don't need Sherlock, just common sense.

If you want an actual answer, the wonderful people of tumblr just gave the 3 most likely combos, so even if it does lock you out after 3 tries, you *should* get it anyway.