I'm new to Hubs, but on another site a group of jokesters would conspire to pick someone at random and on the same day comment on one of their photos with comments that had nothing to do with the photo.
I'm ashamed to say we did it to drive people up a tree, but we were not malicious in any way, and the things we wrote were funny and even poetic. Just entirely off-point.
Sometimes the person 'got it' and then we'd let him or her in on the joke and offer them a place in our little troll group.
Now, this was years ago, before big spamming bots were a problem. I don't know if it would be considered good clean fun today.