Sometimes it's because they're prone to break out into hellish shrieks (see: L5) and other times it's because they rap like they're faded in a library (see: Anycia).
Glorygirl2950 isn't quite as extreme, but on 'Dior Skirt' she alternates battering ad libs (recently most associated with 2Sdxrt3all) and a shrill, scream-rap flow that catches me off guard every time.
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