French
expression used to prank someone who has just said "quoi" ("what" in french).
It finds it's meaning from the fact that "quoi" is pronounced cou-a, so saying quoicoubeh is
essentially saying "cou-a, cou-b", kinda like another popular french joke that occurs when people say "ah" because they are surprised, and you answer "b" because you're
extremely unfunny.