Related Clues:

• Quirk of behavior
• Unconscious quirk
• Start of a simple game
• First X, maybe
• Muscle spasm
• Sudden contraction
• Sign of nerves
• Muscle contraction
• Involuntary twitch
• Recurrent twitch
• Eccentricity
• An X could represent it
• Little jerk
• Peculiarity
• Involuntary muscular contraction