How to Hide Link in Image Preview?

You know what I want, I need to rick-roll some peeps. I've seen people hide links in images and gifs, so that they find out it's a rick roll after clicking "open original."

Not sure how to do this but I suspect it has something to do with HTML coding? Not much info online, or I just don't know what to google I've found people talking about it but nothing on HOW to do it. Anyone know how to do this?