I have a close friend who posts jokes on social media almost daily. Recently, I discovered that these posts are lifted, word for word, from the Twitter feeds of famous comedians and authors. But my friend doesn’t credit them; he acts as if he’s the author. Facebook friends say how clever he is. (The weird thing? He’s funny enough to write his own posts.) Should I say something?   —Name Withheld

Pilfering other people’s intellectual property (or using their work without attribution) is as bad as stealing their backpacks. Your friend’s actions discredit the originality of hard-working writers, even if he has only 100 followers. This joke thief may be lazy or insecure, but that doesn’t matter. He’s a close friend, and his persistent plagiarism needs to stop. The next time you see him, say, “You’re talented enough to come up with your own social media posts. Why not leave John Mulaney alone, or at least credit him when you quote his work?”

—Adapted from “Social Q’s” in The New York Times Magazine