Cake eater comes from the often misunderstood and misattributed phrase, "Let them eat cake!". Many say it was spoken my Marie Antoinette while others say the quote was originally attributed to Maria Theresa of Spain. Supposedly during the French Revolution when the hungry french were begging for bread to eat Marie replied with "Let them eat cake."
According to Wikipedia, it is in reference to "oven cake" which was used to clean out the brick ovens when too much soot and creosote built up; therefore she was saying "Let them eat crap," because she could care less about their hunger.
As the phrase has been misunderstood, many believed that she was saying, "Let them eat cake"; meaning, if they have no bread then let them eat cake, as her wealth and privilege did not allow her to understand that if the poor could not buy bread then they could also not afford cake. Because of this understanding people not of the bourgeoisie refer to the upper class as "cake eaters", people who are so wealthy and clueless of the difficulty that being poor can bring.
Paris: "Oh, my God, that refugee look is so hot! I would totally love to look like that, I don't know what their complaining about; just look at her cheekbones!"
Angelina: "God Paris, you're such a cake eater!"