'''Airdate''': November 2nd, 2008.
After visiting the local spa with his friends, Peter goes to the local Mini-Mart where Chris works. Peter then decides to threaten the Mini-Mart with a lawsuit, claiming that Chris is making "sexual remarks". To prevent a suit, Peter is given an unlimited gas coupon for a year by Carl. Peter begins to take advantage of the card, even taking a trip into space, until Lois suggests that the family take a road trip. They decide to travel to the Grand Canyon. They leave early the next morning (with Peter using a bugle). However, they leave Stewie behind at home. They find out they left Stewie home while at the World Trade Center site in New York (where Peter forgets what occurred on the site).
Despite being left alone, Stewie realizes that he can do whatever he wants, including drinking his first soda. Lois calls Quagmire and Cleveland to take care of Stewie. However, Stewie thinks they are intruders, so the two wind up knocked out. Stewie realizes his mistake, so he chains them up in the basement, where they are forced to watch the [=DirecTV=] help channel.
After not receiving any calls Cleveland or Quagmire, Lois insists that the family return home to Stewie. While driving the car, Peter becomes distracted by the car next to them having a DVD, and somehow enters said car, causing the Griffins' car to crash. The family tries to get tickets home via a train. However, Peter blows all of their money on [[PlanesTrainsAndAutomobiles "shower curtain rings"]]. Fed up, Lois finally [[TheReasonYouSuckSpeech tells Peter that he is a complete idiot that made the trip a living hell]]. Peter fires back, declaring that his friends and kids like him, and that's just the way it is. Lois winds up feeling shame. Brian winds up getting the family to hitch a ride on the back of a truck.
Stewie, meanwhile, consumes all of the food in the house. Too broke to afford food, he applies for a job at McBurgerTown. He winds up eating some fast food, and is fired. Eventually, Stewie realizes how much he depends on his family and is thrilled to see them return. However, he leaves Quagmire and Cleveland in the basement, the latter mentioning that he is getting his own [[TheClevelandShow spinoff]] (in the DVD version, it's replaced with Quagmire having a breakdown over watching the [=DirecTV=] help channel repeatedly).
!!Tropes present in "Baby Not On Board" include (([[YMMV/FamilyGuyS7E4BabyNotOnBoard YMMV Goes here]]):
* EasilyForgiven: Peter's rebuttal to Lois's ReasonYouSuckSpeech manages to make Lois feel bad.
* KarmaHoudini: To go along with the above mentioned EasilyForgiven, Peter once again suffers no consequence for literally almost getting his family killed due to his sheer stupidity and lack of focus. What makes this one especially bad is the fact that he probably wasnt even really paying attention to Lois calling him out and just felt like quoting PlanesTrainsAndAutomobiles.
* TheReasonYouSuckSpeech: Lois manages to dish a harsh one out to Peter, actually stating that a monkey would be comparable to him. Peter conjures up a rebuttal quickly.
-->'''Lois:''' Here's a little tip, if your instincts tells you to do something, '''''don't do it'''''. If your instincts tells you not to do something, '''''it's probably the right thing to do!'''''
** ''HomeAlone'': The subplot of Stewie being left behind and setting traps to capture whom he thinks are burglars (they're actually Quagmire and Cleveland) in his basement.
** ''PlanesTrainsAndAutomobiles'': Peter's speech and the fact that he brought shower curtain rings.
--> '''Chris''': [[LampshadeHanging Haha, movie references!]]
* TookALevelInDumbass: Even by Peter's standards, he's a complete dolt in this one, and Lois lets him know this.