To tease, joke with, or playfully deceive someone. To tell someone something untrue as a harmless prank.
This phrase likely originated in 18th-century Britain, possibly from the practice of street thieves who would literally pull someone's leg to trip them before robbing them. Over time, the meaning softened from actual physical harm to harmless deception or teasing.
The evolution from literal leg-pulling (a criminal act) to figurative leg-pulling (friendly teasing) shows how language can completely flip the emotional weight of a phrase. It's also interesting that this very physical metaphor became so abstract that we rarely think about the literal image when using it.
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