s-word

(euphemistic) The word shit, regarded as a vulgar word.
(euphemistic) The word slut, regarded as a vulgar word.
(Ireland, UK, euphemistic) The word spastic, regarded as an offensive word.
(US, euphemistic) The word spic, regarded as a vulgar word.
Any word beginning with s that is not normally taboo but is considered (often humorously) to be so in the given context; for example, socialism.