It's used only by those who are not only rather unkind, but arrogant with it.
Still, I can't help admitting to a certain glee in knowing a word to describe someone who has a fat bottom.
Tea in the garden, Beryl Cook 2003
Word Not To Use Today: steatopygous. This word comes from the Greek stear or steat- which means fat, plus pugē, which means the buttocks.