Definitely some that are 10 years old. Thinking about it, it's the strange kinky ones I bought when DH and I first got together, you know with feathers and satin and ties he could undo with his teeth. Still look like new, still hideously unsexy. I was a student, what can I say?!
NB, this thread has motivated me to clean out my knicker drawer, no matter how skint I am, I'd rather have less knickers than some of the old ones in there. And why on earth am I holding onto bras some 2/3 cup sizes too small?