Cut down a tree with a herring? It can't be done.
5 seconds sound clip from the Monty Python and the Holy Grail movie soundboard.
You can hear this line at 01:03:15 in the Blu-ray version of the movie.
Quote context
[...]
- Then, when you have found the shrubberies...
- You must cut down the mightiest tree in the forest with a herring!
- Cut down a tree with a herring? It can't be done.
- I cannot tell. Suffice to say, it's one of the words the knights of Ni cannot hear.
- How can we not say the word if you don't tell us what it is?
[...]