Possible Clues:

• Obeyed a laryngologist
• Opened for the doctor
• Got ready for a tongue depressor, say
• Vocalized for the doc
• Obeyed a doctor holding a tongue depressor
• Obeyed the doctor
• Responded to a doctor's request, perhaps
• Awaited a tongue depressor, maybe
• Passed an oral exam?
• Stuck out one's tongue as requested