The whole bit is made all the funnier by knowing that all of the guards were just random extras who weren’t told what was going to happen, only that they weren’t allowed to laugh at any cost as they wouldn’t be paid if they did.
Then there's the scene where it all goes a bit Question Time.
Wonderful quotes from Monty Python & the Holy Grail. Awesome.
Don't You Oppress Me!! -- Monty Python - Life of Brian