Historical clue formulations

• Slip-up — 2020-05-27
• Reason to say "Duh!" — 2020-04-03
• Stupid mistake — 2016-11-13
• Screw-up — 2016-11-07
• Big goof — 2014-08-17
• Big boo-boo — 2014-04-27
• Gaffe — 2013-10-27
• Screw-up — 2013-02-01
• Gaffe — 2012-02-16
• Screwup — 2011-11-29
• Blockheaded move — 2009-11-27
• Boo-boo — 2006-04-18
• Faux pas — 2005-10-20
• Silly mistake — 2003-09-09
• Screw-up — 2002-02-17
• Big boo-boo — 2001-01-14
• Cause for a head-slap? — 2000-10-17
• A bungler might pull one — 2000-01-26
• Fool mistake — 1999-05-23
• Foul-up — 1998-10-14
• Cause for hitting the forehead — 1998-01-11
• Damfool thing — 1997-09-19
• Dumb mistake — 1995-12-26
• Faux pas — 1995-10-30