Willies

google

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late 19th century (originally US): of unknown origin.

wiktionary

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The meaning "spell of nervousness", recorded since 1896, stems perhaps from the woollies, a dialectal term for "nervous uneasiness", probably in reference to the physical itchiness of wool garments.

etymonline

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willies (n.)

"spell of nervousness," 1896, perhaps from the woollies, a dialectal term for "nervous uneasiness," probably in reference to the itchiness of wool garments.