Spriggans are a certain class of Faeries and not all faeries are pretty with wings and glowing clothes. Spriggans are ugly and grotesque in their shape and are known as villains and theives, who are destructive and dangerous. They have been known to rob human homes and kidnap human babies leaving an ugly Spriggan baby in its place. They also create great whirlwinds destroying crop fields or blighting crop fields and any other form of unpleasant mischief they can do.
To call an Irishman from Ireland a Spriggan is an insult, but usually it is because they deserve it.