Nonstandard or very informal contraction of 'were not,' occasionally used in dialectal speech instead of the standard 'weren't.'
Modern dialectal contraction from 'were' (Old English 'wǽron,' past plural of 'be') and 'not,' following the pattern of other reduced contractions like 'couldn' and 'shouldn.'
The fact that 'weren' shows up in some dialects proves that English speakers are constantly experimenting with how we contract words—it's like watching language evolve in real-time in casual speech.
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