Possible Clues:

• Is going back a long way for such rhetorical devices
• Animal analogies, often
• "Free as a bird" and others
• Figures of speech such as 13 across and 4 down
• Many ''as''-in-middle phrases
• 'Smart as a whip' and 'sharp as a tack'
• 'Happy as a clam' and 'blind as a bat'
• "Mad as a hatter" et al
• "Fit as a fiddle" and "free as a bird"
• They use 'like' in a non-Valley Girl way