Right now there is information about a Swag Code Hunt on the Swag Bucks Blog. I am not sure how long these codes are valid.
Copy and then paste the code on the Swag Bucks home page in the box that says: Enter your Swag Code.
If you would like to know more about Swagbucks and why I love it so much (I have earned more than $180 in gift cards since joining about 11 months ago), you can check out this post. Or you can go ahead and sign up here, they will start you out with 30 Swag Bucks!