You've got two empty halves of coconut, and you're banging them together.
6 seconds sound clip from the Monty Python and the Holy Grail movie soundboard.
You can hear this line at 00:05:10 in the Blu-ray version of the movie.
Quote context
[...]
- I must speak with your lord and master.
- Yes.
- What?
- You've got two empty halves of coconut, and you're banging them together.
- So? We have ridden since the snows of winter covered this land. Through the Kingdom of Mercia.
- Where did you get the coconuts?
- Found them? In Mercia? The coconut is tropical.
[...]