Hmm.

Best case scenario: she opens the package, shakes her head, laughs and rightly assumes that hope springs eternal for some poor dude too afraid to approach her directly. She chucks out the gift.

Most likely case scenario: you scare the Hell out of the poor woman because, after all, what kind of stalker creep sends underwear in the mail and demands dirty pics? She sits up at night afraid of being alone, afraid of being watched, and afraid to carry on normal or even flirtatious conversations with other men because who knows if they're the one out there trying to control her without even introducing themselves first? She no longer sees a nice guy as a nice guy - he might be some creep gathering intel.

Almost but not quite worst case scenario: she actually goes along with your note, thus proving to you beyond a shadow of a doubt that the woman you have the hots for is actually a complete and utter moron with no regard for her own safety or reputation.

Actual worst case scenario: you get found out, fired, sued and put in jail. You're on the sex offender registry for the rest of your life.

Rethink this one dude - just sayin'.