Too small polyester button-ups in dark colors look great, or try children's size tee shirts with random slogans.
You can choose from button-ups, t-shirts, and more.
You can't just walk around in an old Beavis and Butthead t-shirt from the 90s and a pair of ratty blue jeans between button-ups and suits.
Button-ups: Though the colors and patterns may change from season to season and designer to designer, you can't go wrong with a button-up shirt.
These shirts tend to be short-sleeved button-ups with collars.