Yes, and glue the cards inside a magazine, then send at printed paper rate, should save you a bit on postage.
Stupid idea. What happens if they X-ray it.... customs will open it up to take a look.
Send it in the kosher manner and declare it. You're not exactly going to be done for millions of import duty on an SD card, if they bother asking for import duty at all.
But as others have said, the real 21st century solution is for the OP to upload and the recipient to download.
You could also put them on a private Flickr album !