I read somewhere the best first response to that kind of lying, say something like, "you wish it was out batteries", at first. I'm past that with my three year old. I've already told him, nobody's going to want to talk to you if you keep on lying. He answered, "what's lying." (he told me he already put his underwear on when he was standing buck naked in front of me).
I can't remember what I was doing the other day, but I was multi-tasking. I told him I was busy doing one thing and he saw me doing another and he told me, "you're lying". And I tell him "don't pester people" enough that he said it back to me when I nagged him about cleaning his room.
