As discovered here, there's an Easter Egg in chat, triggered when trying to set a negative timeout for a chat room. It shows a funny error message:
I’m sorry Dave, I’m afraid I can’t do that.
So, who's this "Dave" fellow?
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It's a quote from 2001 A Space Odyssey by Arthur C Clark, although these days the quote is better known from the film rather than the book of the film, although both were developed and released at the same time.
At this point in the book/film the computer is not just refusing to obey Dave's commands, it is in fact trying to kill him. Hence the appropriateness of the quote in other circumstances when a computer cannot fulfil a human command.