by Prof. jubjub June 15, 2010
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
Year 12 N2 : I’m starting a water balloon fight on the oval
by eedeen November 11, 2021
Similar to 'moving mad' or 'waffling'
by MuckerOfClams October 25, 2023
by Lucas le caribou January 28, 2022
by TheSaviour April 22, 2020