Fed up to the back teeth

Origin

The vivid imagery of "fed up to the back teeth" likely emerged from a common physiological experience: when one is truly full, food reaches even the furthest molars. This sensation of being completely stuffed or overwhelmed found its metaphorical parallel in the early 20th century, particularly within British English. It captured the feeling of having had more than enough of something, pushing the limits of one's patience or endurance until every part of one's being, even the back teeth, registered the absolute surfeit. It quickly became a popular way to express profound exasperation.