muck up

Verb

muck up (third-person singular simple present mucks up, present participle mucking up, simple past and past participle mucked up)

1. (informal, intransitive, transitive) To ruin unintentionally.
   • The terrorists have really mucked up our holiday plans.
   • That’s why they’re called the Founders? Yes, because it will be their job to repair a world that millennials have mucked up beyond repair.2015 December 2, “The Founders, the Plurals, iGen or ReGen – what should we call the post-millennials?”, in The Guardian, →ISSN

   Synonyms:

   mess up, blow it, bobble, boob, crap up, miscue, drop a bollock, drop the ball, err, flub

2. (Australia, informal, intransitive) To clown around; to have fun, often at the expense of others.
   • It's the last day of school and everyone is mucking up.

   Synonyms:

   muck about, muck around, fuck about, fuck around