Understand 'bunk off school' is mainly British slang, less common in other English-speaking countries. She was puzzled by 'bunk off school' until she learned it's a British term.
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Negative Connotation
'Bunk off school' often has a negative connotation, implying mischief or defiance. He developed a reputation for bunking off school.
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Parental Disapproval
Using 'bunk off school' can suggest expected disapproval, especially from parents or teachers. She knew her parents would be furious if they learned she bunked off school.