muck up 

To ejaculate on a girls face

Put your balls in her mouth and get her to hum until you muck up on her face.

muck up by Jumpy June 18, 2006

muck up day 

muck up day is usually when year 12s do a prank similar to senior pranks. mostly used and done in australian public schools

P1 : What are you doing for muck up day?
P2 : tying a year 7 to a pole.

muck up day by eedeen November 5, 2021

Muck up day 

A day where usually year 12s do things that are not allowed e.g tying a year 7 to a pole ect. mostly done in Australia.

Year 12 N1 : What are you doin for Muck Up day?
Year 12 N2 : I’m starting a water balloon fight on the oval

Muck up day by eedeen November 11, 2021

Crate Muck-up 

The time period when Valve released a TF2 update with spaghetti code that forced the crate series to always drop unusuals. This resulted in the unusual market crashing with absolutely no survivors left.

The Crate Muck-up was one of the worst disasters in TF2 history.

Crate Muck-up by FL4ym3Burn July 26, 2019

muck it up

After a good doggie style romp, the jizz left on the tip of your cock gets rubbed into the chicks bunghole. A little poop gets mixed in during the rubbing and you muck it up.

After banging the bitch doggie style, I blew on her back. Then I mucked it up for a bit, before banging her sister.

muck it up by Dr. Davidoff Vilson March 28, 2005

Muck It Up

Muckit is when you take your cock and push it around in your bitches asshole...you smoosh around her shit and your gizz.

After I was done banging my bitch, I mucked it up.

Muck It Up by Dr. Davidoff Vilson May 13, 2005