Related Clues:

• Nervous twinge
• First O, maybe
• Opening in "Hollywood Squares"
• Involuntary muscle movement
• Contraction of a sort
• First X or O, say
• Bad liar's giveaway
• Mannerism or spasm
• Nervous movement
• Personality quirk
• "___-Tac-Dough"
• First O, say
• -- Tac
• A facial twitch
• Spasmodic twitch