If you are already wearing lingerie, then pick out something a little naughtier or sexier than you normally wear.
Remember, you can always give them a romantic poem, and then say "I was thinking of making it much naughtier, but I wasn't sure if you'd appreciate that."
Trashy is debatably naughtier than Frederick's of Hollywood but just as fun.
Intimate Wholesalers has that same style, but they also have a naughtier version, the Black Lace Cupless Bustier with Matching G-string.
If you're looking for something a little naughtier than what Victoria's Secret has to offer, you may get an eyeful of exactly what you'd love to wear or at least admire at Frederick's of Hollywood.