A paradox created when a girl wears a tight shirt to create an illusion of bigger breasts. Tighter the shirt, the bigger the breasts look. Essentially achieves the same effects of a push-up bra but different in a sense of novelty. Push-up bras are fucking noticeable but the tight shirt reaveals the actual size of their breasts.
For example, a girl who is a B-Cup might look like a C-Cup due to the T-Shirt Paradox. However, the paradox doesn't apply to A-Cups. No matter how tight the shirt is, their breasts still look like an A-Cup.
Daquan: "Yo Suzie's titties are bigger than usual today!"
Harold: "It's called the fucking T-shirt Paradox. It just makes her titties look bigger! don't fall for it you dumb shit!"