Possible Clues:

• ''What __ thinking?''
• 'How -- to know?'
• ''How __ to know?''
• "Now, where __?"
• 'Now where ___?'
• 'Now then, where --?'
• 'Now, where --?'
• 'What ___ thinking?!'
• 'What -- thinking?!'
• ''Who __ kidding?''