You're "pretty sure"? You need to talk to a few of the webmasters for other NFL teams who have received cease and desist letters from the NFL for use of logos on t-shirts they were selling. It's not only about using a protected trademark but any confusion it may generate between it and official merchandise. If your concept creates a violation, then bad concept. The biggest challenge in doing a t-shirt like this is avoiding infringement issues. I don't follow the logic here. If the slogan had something to do with tailgating, then I'd see it. If someone is walking in a mall with it on, what would someone think who is unfamiliar with the site? It probably wouldn't be a huge issue if the word "Titans" wasn't part of it. Or, if their symbol wasn't also a part of it. As is, this would bring out "NFL Big Brother" in full force. Don't believe me? Google "trade dress infringement" and "trademark infringement". Then maybe you need to tap into those other ideas. I spent, maybe, four hours on the design I did. But if you need four months, have at it.