When I was little, my Nana used to tell me that it was very important to wear matching underwear, just in case you were hit by a bus. Admittedly, I thought she said 'tin underwear' until I was eleven - I thought it was so your internal organs wouldn't get squashed, and couldn't fathom how you could deal with the uncomfortableness of metal knickers.
It must have stuck - I can't stand wearing non-matching lingerie, and I am obsessed with pretty underthings. Sensible cotton is not for me, I like lace and silk and frills - french cut pants, not the dreaded G-string - ugh. It's the quickest way to make yourself feel good - and even if you're wearing a cotton teeshirt and jeans, you feel like a princess, just secretly.
Stella McCartney and Burberry knickers