We mean it.
This is a good design. No, really.
This is a great shirt. No, we're serious. This is a great shirt. You're not getting it. We really like this shirt. That's why we're selling it. Get it. We really like it. Here, how about this: this is a great shirt. No, but really. We like it. That's why we're selling it. No, we're being honest; we like this design.
Do you guys get our meaning? We like the shirt. We like it. We really do. It's great. Don't you get it? We mean it. Here, let's write it a different way. We truly enjoy this shirt. Ugh. No, that didn't work. Look, what in the heck do we need to say to get this across? What kind of special font do we have to use to hammer it in to your THICK SKULL that we really, truly, actually think this is a good design worthy of selling?
Oh, wait. Here: fun shirt! :D