The below description is taken from LEGO.com.
The Mummy’s favorite thing to do is put ancient mummy curses on people. He just loves it when you wake up with slimy frogs in your bed, or suddenly find your shoelaces tied together, or have your toast always fall on the floor with the butter-side down.
But the Mummy doesn’t really mean any harm, and he’d be surprised if he ever found out that people thought he was being mean to them. As far as he knows, putting curses on people is just what mummies are supposed to do!