Historical clue formulations

• Not say something in jest — 2025-08-30
• Not joke around — 2021-01-03
• Make a declaration with a straight face — 2017-12-12
• Speak with conviction — 2012-09-05
• Be serious — 2010-07-17
• Be serious — 2009-02-19
• "Do you really _____?" — 1993-12-12