quicko: muck up day

Unlike the "level up" so many of my students want to do (for the non-ESL teacher, "level up!!!" accompanied by vast amounts of smiles, tears or gesticulations is the most common way to express the sentiment, "Revered Teacher, it is my dearest wish to progress to the next level of English study.  Do you think I might yet possibly be ready to achieve such heights of academia?"), "muck up" day is the last day of high school wherein students pull various pranks and generally muck about.