The flag itself, but not clothes designed to look like the flag.

IOW: if you’re caught in a sitcom type situation where you lock yourself outside of your house and the only thing you have available to cover your fetus production apparatus is the stars and stripes you fly on your front porch because you’re a jingoistic weirdo, you’re going to be breaking the law one way or the other.

Conversely, the above fashion crime is as legal as brandishing military equipment while shopping in some of the more backwards parts of the country.