I burst out laughing as soon as I saw the title of this thread - my DS has started exactly this. AND if I don't respond then says "I'm whinging for a lolly, Mummy" in an indignant tone.
I have now controlled my response to shriek 'don't whinge' like a crazed harridan, and reply 'could you talk to me in a happy voice please?' in a sick-making 'good example' voice of my own!