The process of putting liquid into bottles; or in sports, when someone loses courage at an important moment.
From 'bottle' (the container) plus '-ing'. The British slang meaning of losing nerve comes from Cockney rhyming slang where 'bottle' rhymed with 'courage'.
British sports fans use 'bottling it' to mean choking under pressure, but the term probably came from Cockney culture where rhyming slang turned everyday objects into hidden meanings that only insiders understood.
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