You will find that an unbranded tee like this is a reliable basic.
Im Not As White As I Look Native American Indian Day Unisex T-Shirt
An unbranded T-shirt like this one is a classic for a reason.
We The People Means Everyone – USA Flag LGBTQ Pride Unisex T-Shirt
This is an unbranded shirt, so you can wear it without any labels showing.
Vintage Croatia Shield Graphic – Soccer fans Unisex T-Shirt
A nice touch is the black drawstring on the hoodie version.
South Korea Trophy Splash Collage Soccer Fans Tribute Unisex T-Shirt
You are looking at an unbranded shirt that feels like a blank page.