Hedgehogs are spiky. They've got quills. They are prickly as well.

As prickly as a hedgehog = it's easy for sb to annoy you or hurt your feelings.
e.g. Be careful what U say to your father today, he's as prickly as a hedgehog.

spiky - по форме, как бе торчащий в разные стороны
prickly - колючий, feels rough and uncomfortable.
e.g. matress hard, blankets prickly; the grass was prickly and cold