loup-loup [lu lu]
A monster or other scary, imaginary being that will frighten a child. Can be used to convince a child to do what you've told them to do.
Often preceded by le gros, which signifies that the monster is BIG!
Ex. "If you don't go to sleep right now, le gros loup-loup will get you!"
My parents didn't often use this one on me, but I sure do remember many times growing up when my sister told me that "the loup-loup" was gonna get me. That's what happens when you share a room with your sister, who happens to be three years older and wiser than you are.
I'll admit it. I was scared of the loup-loup!