The Grim Adventures Of Billy and Mandy Season 3 Episode 15 - Toys Will Be Toys / That's My Mummy >When Billy hangs out at Irwin's house, he finds a living mummy in the bathroom. Seeing as Irwin gets nervous, and as Billy has never met Irwin's mother, he suspects she is the mummy. To scare him off, Irwin's dad tells Billy he has the "curse of the mummy". Billy is attacked by insects and snakes while he tries to find out the truth about the mummy. It is later confirmed that Irwin's mother is in fact the mummy, but no further explanation is given as to how Irwin's family works or how he was conceived.