Historical clue formulations

• Terse reply to "Why?" — 2025-09-18
• Since, informally — 2025-01-20
• Conjunction in a text — 2023-07-20
• Since, informally — 2021-02-01
• Explanation that doesn't explain anything, informally — 2013-05-09
• Slangy response to "Why?" — 2009-11-03
• Since, slangily — 2009-05-05
• Slangy conjunction — 2009-04-16
• Since, informally — 2004-02-15
• "How come?" comeback — 2003-04-13