Definition of crease up

The expression "crease up" originated in the mid-19th century as a result of the increasing popularity of creased clothing. Creasing, also known as pressing, is the process of ironing or steaming garments to create sharp folds and wrinkles to achieve a specific shape or style. The term "crease up" initially referred to the act of creasing an item of clothing excessively, resulting in prominent and exaggerated wrinkles that would often remain even after being worn. This could lead to a stiff and uncomfortable fit, causing the wearer to appear as if they were shuffling or moving awkwardly, as if they were "creasing up" while walking. In the latter half of the 19th century, the expression evolved to describe a person's emotional state, particularly one of uncontrollable laughter or smiling. This evolution derived from the visual similarity between the exaggerated creases in clothing and the involuntary movements and contortions that people make when they laugh or smile excessively. Therefore, to "crease up" came to signify experiencing an uncontrollable and exaggerated emotional response, particularly one of laughter, resulting in a distinctive and memorable physical expression.