Related Clues:

• Eyes-closed event
• 'Bless you!' prompter
• Something that's impossible to do with one's eyes open, per an urban legend
• Dander reaction, perhaps
• Allergic reaction?
• React to dust
• To which one might respond 'Salud!'
• Allergic reaction of a sort
• 'Gesundheit!' elicitor
• Say ''Achoo!''
• 'Bless you!' elicitor
• Hay fever explosion
• Hay fever season sound
• Precursor to “bless you”
• Sound that warrants a blessing