T-shirts can say a lot of things about us. They are almost like a walking billboard of the kind of personality that we have, and can be seen as somewhat of an expression of what we are. Whether or not this is an intentional expression of who we are, or just something that we happen to be broadcasting without us realizing it, it can be symbolic of what we are simply by reading a t-shirt.
If a t-shirt has a message on it, you can tell what kind of a mood a person might be in. If someone is wearing a shirt with a sports team on it maybe they are getting ready for the game. If they have a t-shirt with the name of a band on it maybe they really are into that band or that type of music. T-shirts can also carry slogans of politicians that might be popular, or maybe even quotes from leaders of the past.
If a t-shirt is blank, it can mean that they really don't have anything to say, or don't feel the need to say anything. I used to wear blank t-shirts back in the day. Sometimes just a white t-shirt, or a red or blue t-shirt from Old Navy. I didn't really feel the need to advertise something on my shirts, or tell the world that I shopped at a certain store.
If someone is just wearing a Hanes T-shirt, it could mean that they don't care what they look like, or don't care that they didn't spend a lot of money. Maybe they just woke up in a strange house or were robbed the night before, or it could mean that they don't really care what they look like. Maybe they feel like a simple t-shirt is all they need and don't need to be proving to others what they look like matters.
What about people wearing multiple t-shirts? Some people tend to wear multiple t-shirts. This could mean that they are practical and are always ready. A good undershirt can be a life saver at the gym or if your shirt gets a stain on it or something. You then have another shirt on underneath that without looking like a total dork.
The t-shirt has a lot of symbolic meaning. Some use it to broadcast a message while others use it to tell people they don't care what they look like. Some have a function, and some are the function of ego or being broke.