The word "sarcasm" comes from the Greek sarkasmos, meaning "to tear the flesh." How terribly appropriate.
The youth minister from my high school church group described the old phrase "sticks and stones may break my bones, but words can never hurt me" as one of the greatest lies taught to children. Until he mentioned it, I hadn't noticed how true that is. Of course words hurt. How often do the scars from sticks and stones heal and disappear quicker than the pain of a single careless word? Careless, mind you: not necessarily malicious or angry. A simple slip of the tongue can be just as harmful as an intentional insult, often more so.
...at least, that's the case for me. I'm very sensitive to words. As something of a writer (and a needy, oversensitive type), perhaps I nit-pick over what are, to others, minor verbal issues... miniscule variances of intonation, dreadfully specific word meanings, and often imagined implications. Others among my friends can shrug off sarcasm seemingly without taking a scratch. I can't imagine myself being able to do that, but time will tell.
Sensitivity aside, it's easy for sarcasm to get out of hand. And it's often easy to tell when that happens... you may be familiar with that moment when, in the midst of some friendly banter, someone makes a comment that's just a little too true, a little too close to home. For perhaps a second there is a thick silence, as though everyone had just gasped and were still holding their breath. Then, depending on your company, one of two comments: either "dude, that wasn't right," or more often, "aaaaaanyway..."
One of the biggest challenges in my life is being careful of what I say. I have a very stupid, eager tongue, which wants to slingshot into the world anything and everything in the DO NOT SAY area of my brain. Ask any of the girls I know. Oi, vey.
To everyone who will speak with me anytime soon: remind me to watch my mouth. I need a reminder more often than I'd like.