Possible Clues:

• Hairsplitters
• Know-it-alls
• They're out of step and overfussy
• Bookish types
• Sticklers
• They are over-concerned with correctness of detail
• Balls trapped in underwear — they split hairs
• Uptight nit-pickers
• Nitpicking types
• Rigorists would see opposition leader in underwear