What Was Someone Smoking Meaning

(idiomatic, humorous) Used to express surprise about someone's uncharacteristic or whacky, offbeat past actions.

Example: 1996, Mark Lawrence, A to Z of sports cars, 1945-1990 - Page 1943
  The SGZ is primarily a signal that Alfa Romeo is back in business as serious maker of serious cars although the Zagato body puts one in mind of the FI team owner whose response to a new car was to ask his designer 'What were you smoking when you designed that?'
2005, Gemäse Simmons , Worth Fighting For!: The Tragedies & Triumphs of Professor Renee ... - Page 25
  â€œ...We don't want to live there. It's dark, creepy and it stank. What were you smoking when you bought this place? Hope you bought it real cheap, where is your change at?”
  â€œShut the hell up”, James snapped back. “I'm your daddy and you going to live where I move you”.
2007, Lee A. Iacocca, Catherine Whitney, Where have all the leaders gone? - Page 82
  Bush and company had a fantasy that we could bring democracy to Iraq and it would cause a domino effect in the Middle East. Suddenly every Arab nation would embrace democracy. What were they smoking?