Right, and that's what the topmost poster meant by "buy small and women sizes" -- if you really care, you won't have to say "we don't have anything smaller than a large."
People used to hearing that line really appreciate when you go the extra mile:
That Webstock t-shirt is pretty nice. I think you could take it a step further and make a stylish / designer / funky t-shirt that a reasonably large subset of people will actually want to wear. Not just a blatant ad for your company.