i honestly wish i had the Garfield cartoon on my computer where he is singing on the fence and a neighbor starts yelling at him to shut up and calls him names. Garfield takes it in stride with the childhood rhyme "sticks and stones my break my bones but words shall never hurt me" and then he gets hit full on with a dictionary. it proves a point so beautifully that words can and do wound. these aren't physical wounds (unless you drop a dictionary or thesaurus on your foot) but wounds of the soul. and wounds of the soul fester, in many ways, worse than physical wounds ever could.
words are thrown around thoughtlessly and hurt. they are hurled intentionally to hurt. either way, the wound is still there and it can take months of care to mend what was so carelessly torn asunder by those first words. and, even then, it can be hard to tell if the friendship (or whatever relationship was damaged) has truly mended.
so for all of us, friends and foe alike, take a moment to think before you speak. take your tone and attitude into consideration. would you like to hear what you are about to say directed at you? if the answer is no, then don't say it. because people won't always tell you when what you say hurts. of course, they might and you can just overlook it, but that's another problem entirely and one that won't go away without conscious effort on your part. even if you don't mean to hurt someone, you might, and then there's always that question of what could have been said differently.