What is Shiznitch?
1.
The cat's meow, the dog's bollox, the best.
A nonsense formulation popularised by Tenacious D's lazy urban hymn to love: "My biznitch is the Shiznitch"
See
2.
Word said in place of "shit" when you realize you're in a crowd where the use of shit would be frowned upon.
"Oh, shi-shiznitch!!" Bob said as he accidentally spilled his soda while he was watching a Disney movie while babysitting his nephew.
