Can you lock an iPhone/iPad wallpaper?

I don't know why but whenever I'm not around my sister will take my iPad and change the wallpaper to something annoying. I'm really starting to get tired of it and I'm wondering if there's anything I can do to prevent the wallpaper from changing (besides setting a pass code on my iPad)

Nope, you can't lock it.

No you can't lock wallpapers.

Either tell her to stop or lock the iPad.