They probably spank the cat with a picture of Justin, until the cat starts to associate the picture with pain. Then when they just show the cat the picture, the cat attacks the picture.

I hope no one else does this to their poor cat for a laugh though.

The paper might not really physically hurt the cat, than just annoy it or scare it. But still, the I think the point of owning an animal is to be nice to it and love it, not annoy it, hurt it, or cause it pain to get a laugh.