A senior prank, also known as muck-up day in Australia and the United Kingdom, is a type of organized prank by the senior class of a school, college, or university. They are often carried out at or near the end of the academic year and are part of school traditions. While most senior pranks are harmless, more severe pranks can include damage to school property and other crimes, which can result in disciplinary or even legal repercussions against the perpetrators.