I’ve been trying to locate the source of this exchange without much success, the best I came up with mentioned it was placed on buttons sometime in the early 80’s, but that still doesn’t tell me where these lines originally came from…
“I thought you silenced the guard.”
“Guard? What guard?”
“You Fool, I am the guard!”
Having searched for it, it looks like there are lots of people who quote it, and quite a few are looking for the source- someone says they remember it from a film wit three people walking down a corridor. I have a fleeting memory of something similar being said in Hitch-hikers Guide to the Galaxy or Red Dwarf, although this may have been copied from another source.
The best reference I found came from a suggestion that it might be part of the Dungeons and Dragons tradition-t could have been one of the famous last words in the computer program or books:
Listed as ‘Advanced Dungeons and Dragon’s Last Words’:
Someone mentioned that they could just as easily picture the Three Stooges; Curly, Larry, and Moe in the same situation or for that matter, the Bowery Boys or numerous other comedy teams doing it.