All you have to do is send them a post card and in return they will send you a free t-shirt!
Here is what they posted on their facebook:
We are loving our consumer postcard map!!! We put it together on Friday. Soooo, we need more postcards from the midwest and west. Send postcards of where u live to us and we will send you a free t-shirt ;)
Send them to: Wholly Marketting
300 burlington road
saginaw, tx 76179
Make sure to include your address, so they have a place to send the t-shirt!