Pffft tell the asshole where to go, you don't need to do things like this, a nicer client will soon replace him.
Even if not illegal to walk about with everything on show (although I am sure it would fall under public indecency laws), you have to think about other people, there could be children about or even just those who would find it awkward.
Remember your the one in control, you can tell client to F off :-)