Question - Changing image?

[Lune.]

So, I've seen people in their signatures have an image, but whenever the page it reloaded the image is changed. Could anyone explain to me how to code that in BBCode? Sorry if this has already been answered ^^'

[Keir;]

You actually have to use another site to do that, it's not done with BBCode - use this website to add all the images you would like to rotate through, and then it will give you a single url that you put between the [img] tags like you would any other ^^