Babyfier, A.K.A. Experiment 151, is an illegal genetic experiment created by Jumba Jookiba. He is designed to throw entire planets into chaos by turning the population into babies; the antidote consists of two teaspoons of applesauce, one cup of milk, three mashed bananas, and a dollop of 100% Kona coffee. If left uncured, any de-aged victim will have to grow up all over again. His one true place is at the dog pound, where he turns old dogs into adorable puppies, thus making them more appealing to potential adopters.
Experiment 151 was the 151st genetic experiment created by Jumba with Hämsterviel's funding. He was designed to turn entire civilizations into babies, throwing the planet into unsupervised chaos. 151 and the other first 624 experiments were deactivated and smuggled to Earth by Jumba during his mission to capture Experiment 626.
All of the experiment pods were released and scattered across the island of Kauai, with 151's pod landing on a sidewalk.
When the Ice Cream Man tripped on 151's pod, it rolled across a nearby beach shore and into an ocean wave, activating the experiment. 151 then proceeded to turn the tourist into a baby, causing him to behave like an actual infant.
Later, 151 went on a rampage, turning others, including a construction worker, into babies before Stitch was able to capture him in a containment orb.
That night, Stitch released Babyfier on Nani so Lilo could be in charge for once. However, after turning Nani into a baby, Babyfier turned Stitch, Jumba and Pleakley into babies too. Babyfier then attempted to turn Lilo into a baby as well, but the former was lured into a trap and recaptured.
When Experiment 625 discovered that Babyfier turns adults into babies, he released Babyfier on Gantu. However, after turning Gantu into a baby, Babyfier attempted to do the same to Reuben, causing the latter to lock Babyfier out of the ship. The ruckus alerted Hämsterviel, who then demanded them to retrieve Babyfier.
Meanwhile, the babyfied Jumba (who still retained the knowledge and intellect of adult Jumba) managed to find a cure on his computer that would reverse Babyfier's effects. Lilo despaired when she saw that one of the ingredients for the antidote was a dollop of 100% Kona coffee, which only adults were allowed to buy.
Outside with her infantile ʻohana, Lilo tried coaxing a passing couple to buy her the required coffee before Babyfier turned them into babies. Lilo, the babyfied Nani, and the babyfied Stitch chased after Babyfier as he went on a second rampage, turning countless victims throughout Kauai into babies.
Meanwhile, the babyfied Jumba and Pleakley traveled to Kiki's Coffee Hut, where they found several bags of 100% Kona coffee on a shelf to make the remedy for undoing Babyfier's effects.
Later, the babyfied Stitch and Gantu tracked Babyfier down to a playground, where the two fought over him while bickering, with Stitch winning. Babyfier was then recaptured before Jumba and Pleakley (back to their original ages) arrived with the antidote. With Stitch's help, all the babies on Kauai except Gantu were turned back into adults.
Babyfier was then found a one true place at the dog shelter, where he turned old dogs into adorable and more adoptable puppies, effectively giving them a second chance.
It is presumed that the babyfied Gantu was somehow turned back into his adult self, while Reuben was forced to babysit Gantu in the meantime.
In "Ploot", Babyfier was one of the second team of experiments (along with Finder and Drowsy) formed to try and stop Ploot. However, Ploot was easily able to defeat them, forcing the three experiments to retreat.
Later, the first 624 experiments, including Babyfier, were rounded up by Leroy and taken to a stadium to be destroyed. However, Lilo, Stitch, Jumba, Pleakley, Reuben and Gantu arrived before the experiments could be destroyed.
Babyfier participated in the following battle between the experiments and the Leroy clones by turning Leroys into babies.
However, the Leroys soon gained the upper hand in the battle, but were defeated when Lilo, Stitch, Reuben and several other experiments performed the song "Aloha `Oe", which caused the Leroy army to shut down due to the original Leroy's fail-safe.
Babyfier made an appearance in Season 2 of the Stitch! anime along with Hammerface, Link, Spike, and Woody. He makes a second appearance in Season 3, reprogrammed by Hämsterviel to transform his victims into toddlers instead of babies (and appropriately renamed Toddler-fier). He left Stitch in charge of several schoolchildren whom he turned into toddlers, including Yuna herself.
- Even though Stitch was not born as a baby (being a genetic experiment), Babyfier still managed to turn him into an infant.
- This happens again in Leroy & Stitch, as in one scene, Babyfier turns three Leroy clones into infants.
- This also shows that while experiments cannot age older, their age can be reversed. This is further supported in "Skip", as when Skip went forward 10 years twice, he, Stitch and Reuben didn't age one bit.
- Babyfier's pod color is white.
- Babyfier is described by the experiment computer screen as, "Experiment 151. Primary function: Infant maker. Change the victim into their infant form."
- Babyfier's tail appears in the online game Jumba's Lab.
- Babyfier bears some resemblance to Mew from Pokémon, even having the same designation number, 151.
- In the anime episode "Link-age", Reuben states that Babyfier's favorite type of sandwich is puréed carrots.