This is a test of commonsense. Complete the next sentence:

How to make your breasts smaller
Use a minimizing or sports bra.
Minimizing bras are specialty bras which specifically add no bulk. They help a little and may be enough for your purposes, especially if you're just wanting to fit into particular clothes.
Sports bras, however, not only provide support but also flatten your chest. These originally served the purpose of stopping breasts from moving during exercise, causing pain.