Plural of durr; multiple instances of the interjection, or a dialectal plural form.
Plural form created by adding '-s' to the interjection durr, though interjections typically don't pluralize in standard grammar.
The fact that people even write 'durrs' shows how internet culture is changing English grammar—interjections are becoming countable, which would have horrified linguists fifty years ago but perfectly captures how memes work.
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