Wiktionary
vb. 1 (context transitive English) To ruin unintentionally. 2 (context intransitive English) To clown around; to have fun, often at the expense of others.
WordNet
v. make a mess of, destroy or ruin; "I botched the dinner and we had to eat out"; "the pianist screwed up the difficult passage in the second movement" [syn: botch, bumble, fumble, botch up, muff, blow, flub, screw up, ball up, spoil, bungle, fluff, bollix, bollix up, bollocks, bollocks up, bobble, mishandle, louse up, foul up, mess up, fuck up]
soil with mud, muck, or mire; "The child mucked up his shirt while playing ball in the garden" [syn: mire, muck, mud]
Usage examples of "muck up".
And, of course, they never had to worry about such a powerful personage as Ortega ever coming home to muck up the local works.
He was going to return to what would be a new nation, and I could not muck up his chances, not when he had made a direct appeal to me.
I hope so, he thought, and I hope Alvito's in the muck up to his nostrils.
Henry, while you've got a little sense left: don't let that sour-balled puss muck up your life for you, do you get me?
I do think the relic of a long-dead master Necromancer will muck up Soren's search spell in very interesting and entertaining ways.
Two human skulls, muck up to their nose openings, stared through empty eye sockets.
It also meant that, to be sure that mere people didn't muck up the sophisticated calculations which the system was making on their behalf, all the windows in the buildings were built sealed shut.