(informal, transitive) To ruin unintentionally. / (informal, Australia, intransitive) To clown around; to have fun, often at the expense of others.

plural of muck-up

(informal) The act of botching something; an incompetent mistake. / (Australia, informal) A prank.

simple past tense and past participle of muck up

Third-person singular simple present indicative form of muck up

present participle of muck up

plural of muck-up day

(Australia, informal) The final day of the senior school year, when departing pupils sometimes play pranks.