|Guess Who's Going To Be Dinner|
|Original broadcast||October 24, 2008|
|Series||The Secret Saturdays|
|Overall episode number||5|
|Written by||Eddie Guzelian|
|Directed by||Scott Jeralds|
|Previous episode||The Ice Caverns of Ellef Ringnes|
|Next episode||The King of Kumari Kandam|
Doc and Drew decide to go out together on their anniversary and leave Zak, Fiskerton, Komodo, and Zon to the care of fellow Secret Scientist, Dr. Arthur Beeman. They trick Dr. Beeman into thinking Zon is a UFO. Beeman leaves the house to return to his lab to get the "proper equipment" to monitor the UFO. Zak and his cryptid friends have the run of the Saturdays' house and decide to have some fun.
But, a strange man named Pietro "Piecemeal" Maltese invades the Saturdays HQ, and Zak realizes part of their UFO diversion caused the house's systems to reboot, leaving them with no power to call for help. Piecemeal pursues them throughout the house, intent on making a meal of Fiskerton. Eventually, the house's systems complete their reboot and Zak uses his mother's fire sword to blast Piecemeal through the house's wall and into the water below. At the very end, Piecemeal is seen surviving the fall and crawling out.
- The title of this episode is a take on the movie "Guess Who's Coming to Dinner."
- Dr. Arthur Beeman references the original Ben 10 series by saying "sweet Galvan Prime," the home world of the Galvans.
- It is hinted that Doc and Drew have a bad anniversary when Doc says, "Next anniversary, back to the squid intestines."
- The Headmaster of the Legion of Garuda is seen briefly while Zak is checking the Interpol Criminal Database for Piecemeal.
- Zak briefly uses his cryptid powers in this episode. When he was holding his mom's fire sword up as it was being charged up by the solar lighting, you can see Zak's eyes glowing orange. This means he was around another mystic hotspot. Since he was around a lot of cryptid plants it made his power stronger than ever.
- This is first time that Zak uses the Tibetan Fire Sword.
- During their previous anniversary, Doc and Drew were somehow trapped inside a squid.
- More of the Saturday HQ is shown during this episode.
- We learn that the Saturday HQ has a kitchen, a place for the Saturday Sub, a weapons vault, cryptid plant area, airship landing pad, and a carrier for the airship. The home also expands to a few feet underground.
- You can see Zak's green band in the elevator after Komodo tore it off, but then it disappears.
- Zak setting traps for Pietro "Piecemeal" Maltese is similar to Home Alone when Kevin McCallister sets up a bunch of booby traps to catch the two bad guys.