Muck Fizzou = Fuck Mizzou, or the Missouri Tigers. There is a big rivalry between MU and KU; Used by Kansas University (KU) Jayhawk fans, and is on some t-shirts.
I love the t-shirts that say "Muck Fizzou!"
A term coined by KU's biggest fans which is put in a nice way of saying: Fuck Mizzou! Also, describing how bad Missouri is and they are the biggest bastards in the world. Rock Chalk Jayhawk, Go KU!
If Missouri comes to play in KU's territory, everyone will chant "Muck Fizzou"