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.
by eedeen November 6, 2021
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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
by eedeen November 11, 2021
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