Well, this next one isn't exactly a joke, but a rather amusing situation that occured for me while playing Zork the other day (sorry if it doesn't fit into the topic).

Computer: It is possible to climb down into the canyon from here.
Me: climb down into the canyon
Computer: I do not know the word "canyon".
Me: climb down invisible ladder
Computer: You can't see any invisible ladder here!
Me: of course I can't you bloody moron, it's invisible!
Computer: I don't know the word "course".
Me: Get a new processor you lameass computer!
Computer: I don't know the word "processor".

and so it went on...