Historical clue formulations

• Not what you'd expect — 2023-12-23
• Like things in "Ripley's Believe It or Not!" — 2014-05-09
• Strange — 2010-06-01
• Not right — 2002-08-23
• Eccentric — 2001-07-11
• Strange — 1998-11-09
• Odd — 1998-10-08
• Irregular — 1997-02-25