Buttocks décolletage is a fashion in which the person deliberately wears her jeans or other clothing short or low enough to expose the upper part of the cheeks and crack.
The dress I tried on allowed too much buttocks décolletage, even for the Gulf Coast beach hangouts.
A sunburn or suntan focused on the left arm. It is caused by the left side of the body being the only half that gets exposed to sunlight while driving. Presumably, it would be located on the right side of the body in countries where they drive on the left side of the road.