Never comment on a woman's rear end. Never use the words 'large' or 'size' with 'rear end.' Never. Avoid the area altogether. Trust me.
Women are like cars: we all want a Ferrari sometimes want a pickup truck...
The betrayal of trust carries a heavy taboo.
The properties which differentiate living matter from any kind of inorganic imitation may be instinctively felt but can hardly be formulated without expert knowledge.