For those that haven't seen the movie, the Knights Who say Ni are from the movie Monty Python and the Holy Grail. They stopped King Arthur and his knights and would not allow them to pass without finding a piece of shrubbery. All the while the Knights keep saying 'Ni', which is completing unbearable to King Arthur and his knights.
When they find the shrubbery, King Arthur and his knights return and the rules are changed. The knights themselves change into the Knights Who Say 'ekky ekky ekky f'tang zoom-boing znourringgggmmm'. This is just as unbearing as 'Ni' for the King and his knights. King Arthur and his knights must then chop down the mightiest tree in the forest with a herring.
During this second conversation, the Knights Who Say Ekky.... go into seemingly uncontrolable fits whenever King Arthur and his knights say the word 'it'. King Arthur and his knights, being the dense type, never catch on to what word sets them off.