Truly evil. Spent lots of time removing them from our farm. I'm convinced the thorns are covered with a pain inducing toxin. Got one embedded in the back of my arm once. It broke off just under the skin. Felt like my arm was on fire. Ended up in the ER to get it removed.
Ugh, yuck. I heard a couple stories of surgical thorn removals at today's event! I had a icky run-in w/ a cactus thorn at a O' event in AZ. Once is enough for me.