Edit: Answered! It's sen-sen, a licorice breath freshener. Thank you, Mastodonians!
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I need somebody who is reading (or has read) WITCHCRAFT FOR WAYWARD GIRLS by Grady Hendrix to tell me what the "little black grains" Fern's doctor shakes out of a paper box and puts on his tongue are, because I'm listening to the audiobook and absolutely cannot parse that word. Sin-sin? Fen-fen???
