Backless Garments in School
I think Phil is correct! There is nothing so lewd about girls exposing their backs via wearing a halter top to school. Its not like that are attending as totally topless!
Go to the mall on a hot Summer Day and see how many girls you find with their backs exposed! Try calling them prostitutes for wearing a halter top!
If a girl exposes her back is considered lewd, then perhaps the girls should keep their faces covered as well!