It's visual irony. The characters depicted are usually the least likely to say the things associated with the trolling, and/or would be amusing to imagine the j

It's visual irony. The characters depicted are usually the least likely to say the things associated with the trolling, and/or would be amusing to imagine the juxtaposition. This is why sometimes you sometimes see trolls use western cartoons, celebrities, or modification to popular trends (rainbow flags, olypmic rings, etc.)