squick v. to disturb, unsettle, make uneasy; to cause disgust or revulsion; to gross (someone) out; to freak (someone) out. Also noun, something which causes disgust, revulsion, or uneasiness, or the disgust, revulsion, or uneasiness itself. Also squick (someone) out. Etymological Note: There is inconclusive evidence this term may have originated among practitioners of sexual bondage or sadomasochism. (source: Double-Tongued Dictionary)
Further reading
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Unlike some near synonyms, “squick” does not suggest that the activity in question is morally objectionable or that the disgust is universal—merely that it is decidedly not to the squicked person’s taste.
(Bad porn squicks me. Rapists disgust me.)
What squicks me is the idea that there is not a REASON for disgust. No, it doesn’t squick me, it disgusts me. There are right and wrong actions, and to ignore the morality or immorality (yeah, I know; many of you think it’s a dated concept) of a certain action, just because it “feels good” to the person participating in it, denies our basic humanity and reduces us to animal level. The term “squick” is a way to attempt to get around that disgust at immorality, and it’s nothing more than a ruse.
Sometimes there aren’t reasons, just personal tastes. I’m familiar with the word from fandom circles (used for a good 15 years) to describe fanfiction tastes. I fail to see how morality has anything to do with whether you prefer Spock topping Kirk or the other way around.