Four inches

Something that is mediocre, but there's nothing you can do about it; when a person isn't happy with something but will be polite and accept it. The word originates from the idea that a four inch penis really isn't okay, but a normal partner's response in the moment would be a polite, "oh, it's four inches? That's fine." It's the only appropriate reaction when you've already hit the point of no return in a situation and there's no un-awkward way to back out of it.