The phrase "człowiek, który wiedział za dużo" in Polish translates to "the man who knew too much" in English. It refers to a person who possesses knowledge that may be dangerous, sensitive, or incriminating, often implying a threat to others who want to keep that knowledge secret. This phrase is also used as a title for various works, including books and films, often involving mysteries or conspiracies. For example, there is a notable Polish book titled "Człowiek, który wiedział za dużo" about the murder mystery of former premier Piotr Jaroszewicz and his wife, highlighting that he might have known secrets that led to his death. Similarly, the phrase is known in a broader cultural context as a metaphor for someone with dangerous or forbidden knowledge.

In everyday use, the phrase can imply caution or danger related to the knowledge someone holds, similar to the English idiom "curiosity killed the cat," suggesting that knowing too much can lead to trouble.