Basque occasionally blocks strike approval (6-2)

I believe the answer is:

thumbs-up

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But I can't explain it at all! Could you help me understand?

(Other definitions for thumbs-up that I've seen before include "Okay sign" , "Unfamiliarity" , "Digital sign of approval as in Roman Colosseum" , "Green light" , "Elevated digits as sign of approval" .)

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