The abbreviation of Muck Up Day; a tradition that occurs in many schools (mostly private) on the last day of lessons for year 12s. Pranks are pulled on the rest of the school, including kidnappings, stink bombs, cod liver oil on banisters, viagra in the water supply and releasing three sheep labelled 1, 2 & 4 onto the school grounds (the groundsmen look for sheep #3 which doesn't exist). Students also personalise their uniform (rip it up...).

Water guns/bombs are also used and occaisonally students will hiijack the PA system.

School shirts will often be signed with 'MUD (insert year)'.
student one: did you hear that some of the guys hijacked the speakers in the main hall on muck up day? You should have been there...

student two: I can't wait for our muck up day. Wooo! MUD '11.
by keep.calm.and.carry.on.x May 14, 2010
not cool, or ugly.
example one:
mate1: bro, me and your ex had a root last night
mate2: aaaw bro, you're mud.

example two:
mate1: wow, look at jess, shes mighty fine today
mate2: dude, shes mud.
by bossking November 11, 2011
Making up dumb shit

The blurting out of random words, catchphrases, or facts that are clearly unfounded or do not exist.

Usually brought on by excessive alcohol consumption and/ or sleep deprivation.
Guy#1- that's not right.

Guy#2- dude, I just read a study that 90% of Americans believed that dinosaurs were killed off by alien invaders.

Guy#1 - Stop with the muds. Let's go. You've clearly had too many beers.
by hashtag101 April 03, 2011
Something that is very ugly. Hence, it is ugly as mud.
"Dirty, smelly, ugly"


When someone does something really dumb and it's not cool at all.
"BOY: You see that girl over there?
she's not wearing makeup today.

GIRL:OMG, she's so mud without it."

That guy tried to do a back-flip and he smashed his face in.
He's mud.
by aguido June 13, 2010
fuck frements mud at dota
by Allen~ June 02, 2011
Mandatory Ugly Dress. Often encountered when appearing in a friend's wedding, bar mitzvah, or other ritualized ceremony.
Jenni is such a bitch; that MUD for her wedding cost me $240!!
by LaraS November 06, 2007
A term used for slutty girls meaning, "Multiple Unprotected Dicks Syndrome".
John: The girls of the sorority next door are coming over tonight.
Dave: All of those girls are MUDS...I don't want to catch herpes, get them outta here!
by NWMSU November 23, 2009
Acronym for Multi-User Dungeon. A MUD is a MMORPG(also an acronym for Massive-Multiplayer Online Role Playing game) that is mainly text-based. Most MUDs are coded in C++ and free to both play and use. Players can connect to a MUD server via Telnet, ZMUD, MUSHclient, or GMUD.
"One of the more successful MUDs today would be Achaea."
by Patrick Breeden January 25, 2004

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