Why talk about and wear a shirt for your startup and not even put a link to it? Nobody knows what your startup is, write for an audience that doesn't know you.
That's the catch - for the shirt to be effective as advertising, people who see it need to know what it is.
In the absence of any previous knowledge of the startup, most people would simply assume that "Grouper" is a clothing company, or has something to do with fish products.
Why talk about and wear a shirt for your startup and not even put a link to it? Nobody knows what your startup is, write for an audience that doesn't know you.