Definition of muck up

The word "muck up" originated in the mid-19th century in British schools, specifically in the context of pranks and mischief-making among students. It comes from the phrase "mucking about," which means playing around or causing trouble. "Muck up" literally means to make a mess, but in this context, it refers to disrupting scheduled events or activities, such as exams or ceremonies, usually by practical jokes or pranks. The word "muck" itself is derived from the Old English word "mucg," which means mud or dirt, and it was commonly used to describe farmers' work and manual labor in fields and farms. Over time, the term "muck up" has evolved to mean disrupting or spoiling something in a more general sense, beyond just school activities.