"What Beej means is that he's able to change reality or even himself. He's actually more akin to the Lovecraftian creature known as Shoggoth. It's his last name actually." Lydia explained. 

"Wait, your name is Beetlejuice Shoggoth?" Malcolm asked, raising an eyebrow. 

"His middle and last name." Ash replied with a smirk. "His first name is-"