Curiosity killed the cat.

What it means

Investigating something that is not your business can bring trouble on you. Usually a warning to stop asking or stop looking, delivered somewhere between playful and genuinely sharp.

Where it comes from

The older form was “care killed the cat”, where “care” meant worry or sorrow rather than looking after someone. It is first recorded in Ben Jonson’s play “Every Man in His Humour” (1598). “Curiosity” replaced “care” much later — the earliest known printing is in an American newspaper in 1898 — and the softening tail “but satisfaction brought it back” is later still, first traced to a Pennsylvania paper in 1912.

Example sentences

• “He went through the old files out of interest and found out he was being made redundant — curiosity killed the cat.”
• “Don’t open it. Curiosity killed the cat.”
• “She asked one question too many at dinner, and curiosity killed the cat.”

When it fits — and when it does not

Light between friends, genuinely warning-off from a superior. The reply “but satisfaction brought it back” is common and defuses it.

Similar phrases

• Let sleeping dogs lie.
• Mind your own business.