Test cards
Some people don't like to look at flashing/blinking images on screens, because it triggers migraines or epilepsy or something. What if some TVs are like that and dislike displaying certain types of images on their screens?
When your pal playfully sends you something vile, you might reply with 'How dare you make me see this with my own two eyes?' TVs might say something like, 'How dare you make me display that with my own cathode?'
Some textures are nice to pet (fur, etc.) Maybe some patterns of pixels feel nice for TVs to display on their screens. Some people like the texture of velvet, some people hate touching it. Maybe two TVs are comparing their favourite test card patterns and one of them loves this particular card and the other one is like 'ugh, how can you stand it'.