>>Among the questions you can't possibly answer truthfully, the most notorious one is "are you there?".
>>
>>If I say yes, I'm lying - I'm always here, never there.
>>
>>If I say no, I'm lying - the guy will know I'm there as soon as he hears my voice.
>
>Unless the guy will answer from a direction not implied by 'there' , such as very close by.

In which case the question makes no sense. He's still here, and the question was about there.