You Cannot Lie in the Zone of Truth
Something has been stolen from me, and I intend to find out who has it. My suspicions lie with our rogue, so I turn to him and 'I cast Zone of Truth!'
'You don't have Zone of Truth', says Krunch.
'Well, don't tell him that, magic is mostly showmanship anyways. Okay, gnome, you're now in the Zone of Truth!'
'No I'm not.'
'Okay, that's true. So... maybe the Zone of Truth is working. Gnome, do you have my gem?'
'No.'
'Hmm, technically it's not my gem, so the question was worded poorly.' The Zone of Truth is a fickle mistress and turns out to be more difficult to manage than I realised. I let the matter lie a little longer, which worked out well when a bandit tried to stab the gnome in his sleep later that night to get the gem.