I've been observing beach breast ettiquette. It seems that it's social acceptable to display ones bosoms at the beach so long as one is lying or sitting still. For some reason this is not rude, obscene or even slightly risque.

However if one walks or swims or even stands one must put ones bikini top back on. It's true - I've been watching (not too closely though - lest someone take offence).

A sunbathing beauty will, upon ceasing to bake, cover up to swim. Bouncing bosoms on the beach are inappropriate.