A way of saying that a stripper has one big, fat ass without her knowing it. Using the safe assumption that strippers don't know French, they will think that they are being complimented when you are actually stating that they have one big, fat ASS.
Alex: Yo James, isn't that your ex girlfriend on the stage?! She definitely now has one beaucoup booty.
James: Oh snap! That is her! I can't believe she became a stripper. But she definitely had a fat ass when we were dating. Just the way I like it
Beaucoup Booty: coming from the French word for lots of or abundance and the American word for Butt or Money. Other spellings include Boku Booty or Bocu Booty.
James: Hey man, you should totally move to NYC we Have Beaucoup Booty out here.
Alex: That sounds epic! I will totally move to NYC!