I just read about the "You won a wal-mart card" scam a couple weeks ago. Do NOT respond or you will be stuck with insane cell phone bills from some stupid company you haven't heard of, and it is a pain to get "unsubscribed" from this service you inadvertently "subscribed" to by simply texting them back.
Oy, I'm so glad I have an old-school phone and don't care about texting.