Who is Sherlock?

Kate had a princess party for her birthday. She dressed as Cinderella and we bought her a Cinderella necklace to go with her outfit. She loves this necklace, then again, so does Reilly.

Today I was getting an outfit for Reilly because we were running late. I picked out his Spiderman boxers from his underwear draw and underneath them I found the Cinderella necklace.

I'm confused? What was Cinderella doing with Spidey in and underwear draw. Do I dare ask Reilly to explain?