Re: attention girls: embrace your inner twitch.
Just to second this - it's always been my experience that they show up in a plain cardboard carton.
Course, you could always order it from a place that offers gift-wrapping to cheer yourself up.
(Though that could backfire if everybody wants to see you open your present, so maybe not.)
i can't speak for all possible stores, but whenever i've bought such items online, they've come in rather plain packages, i.e. no big label on it that says "MENSTRUAL PRODUCT!!!"
i've heard that you can buy them at health food type stores, but i haven't checked.
Just to second this - it's always been my experience that they show up in a plain cardboard carton.
Course, you could always order it from a place that offers gift-wrapping to cheer yourself up.

(Though that could backfire if everybody wants to see you open your present, so maybe not.)