I got this today too. If you have Verizon and still have the message, you can follow the instructions below to report the spam to them.
Taken from Verizon's website:
http://support.verizonwireless.com/faqs/Features%20and%20Optional%20Services/spam_controls.html
How do I report unwanted text messages for investigation?
If the message is still on your device, follow the steps below to report the unwanted message:
Forward the suspected spam text message to short code 7726.
Once received, we’ll send you a text message asking for the “From” address.
Reply to us with the “From” address of the unwanted message listed in the body of your text message.
A free text message with a “Thank you” notification will be sent to you to verify receipt.
The investigation will begin.
You’ve successfully reported an unwanted text message.
Notes:
You won’t receive any further updates once you’ve received the final “Thank You” text message.
There are no charges for messages sent to or received from 7726.