Hit a ball with a bat in baseball or cricket, or fluttered or blinked eyes repeatedly.
From Middle English 'bat' (derived from Old French 'batte' meaning 'a stick or club'). The verb 'bat' as in 'flutter eyelids' is a separate origin, possibly imitating the motion.
The physics of a baseball bat is wild—when you hit a fast pitch, the collision happens in about 0.001 seconds, and the 'sweet spot' on the bat actually vibrates less than the rest of it, creating the perfect energy transfer!
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