It is nice but you assume that we are all thin. Some of us wear 3XL shirts.
Though it doesn't say so on the site (yet), they do have different sizes. I ordered the hat before the t-shirt was listed on the site, so I wrote in to customer service to see if I could add the shirt with my pending order to avoid a duplicate shipping charge. The company that oversees the operation (Gameplanz Inc) contacted me to get this done and in the process she asked me what size I would like.
They do have a section for adding comments when you place your order. I imagine if you specify what you're looking for that they'll get it right. Can't say if they have 3XL, but I can verify that they carry XL, as that's what I ordered.