Squeak fulfills what he is programmed to do, which in this case is to annoy enemies by talking constantly. Although not malignant, he is energetic and talkative for hours on end without stopping, tiring out, or even showing signs of needing to breathe. Despite being programmed for nonstop talking, Squeak seems to have some level of self-control as shown when he annoyed the original Leroy by talking incessantly, after which Leroy threateningly shot a blast at him, causing Squeak to immediately become quiet.
Squeak can speak fluent English and go on talking nonstop for a considerably long amount of time. He can talk extremely fast in a high-pitched, squeaky voice, hence his name.
Experiment 110 was the 110th genetic experiment created by Jumba with Hämsterviel's funding. He was designed to irritate people and entire populations by talking nonstop constantly. 110 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.
At an unknown point after this, Experiment 110 was activated and captured by Jumba.
In "Spike", Jumba tested a reprogramming device on 110 (later named Squeak) to make him less talkative without success, as the device just exploded. Even Pleakley was driven insane by Squeak's incessant blabbering, and begged him to stop talking.
The first 624 experiments, including Squeak, 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.
Squeak participated in the following battle between the experiments and the Leroy clones, but was briefly threatened by the original Leroy's plasma gun when Squeak wouldn't stop talking. He also made a referee whistle sound when Kixx punched a Leroy clone over one of the stadium's goalposts.
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 ʻOe", which caused the Leroy army to shut down due to the original Leroy's fail-safe.
Squeak has made three appearances in the Stitch! anime: once in the second season where he was with Frenchfry, Pix, Tickle-Tummy, and Houdini and twice in the third season where he was with Shrink, Clip, Nosox, and Retro.
In the second season episode, "Hämsterviel's Epic Secret", he was captured by Hämsterviel, but was kicked out and blasted to Earth along with Frenchfry, Pix, Tickle-Tummy, and Houdini for being practically useless. However, unbeknownst to Hämsterviel, Squeak took a silent revenge by stealing a purple treasure chest containing one of Hämsterviel's most personal possessions....
Later, the rejected experiments were brought to Yuna's home after being captured by Stitch. Squeak, being the only one of the five that could speak normal English, explained that they were captured by Hämsterviel, but left due to the horrible working conditions. However, Jumba doubted that he would've just let them go, so Squeak admitted that he kicked them out.
After that, the experiments went into training to learn how to fight. However, Tigerlily easily beat them. Squeak then said that they're just not fighters. Yuna then got the idea to find the experiments homes on the island that made use of their seemingly useless powers. While they did this, Squeak gave Hämsterviel's treasure chest to BooGoo for safekeeping.
Eventually, Squeak was the only experiment who hadn't found a home yet. He, Stitch, and Yuna sat on the beach trying to think of something while Squeak rambled on about the ocean. Eventually, Stitch built a giant sand castle around him to keep him quiet. However, Penny then came and demanded that Stitch and Yuna leave "her" beach (it's not, though she claims it will be) before she put them to work in her father's pineapple factory. Squeak then ran out of the sand castle, claiming he loves pineapples. He and Penny started a conversation, each one talking about different things, and walked off. Yuna and Stitch were then satisfied that Squeak had found a home.
Later still, Gantu learned from Pix that Squeak took Hämsterviel's chest. He and Penny were at her house, still talking about different subjects, which Penny claimed was good because what she's saying was all she cared about anyway. Kenny, sick of all their talking, told them to be quiet, only to see Gantu out their window before he broke in. He demanded to know where the chest was, and Squeak said he didn't have it anymore. Yuna and Stitch intervened, and eventually came across a purple treasure chest in Penny's room. Thinking that's Hämsterviel's object, everyone except Squeak chased after it.
When Yuna was confronted by Hämsterviel, Squeak and the other "useless" experiments arrived to help and Houdini turned them all invisible for unforeseen attacks. The chest was later revealed to belong to Penny, and was filled with her failed quizzes.
BooGoo later delivered the real chest, which turned out to be a book of poems that he wrote, which were bad. Squeak and the others shared a laugh at them.
- According to what he says in his first appearance, Squeak's astrological sign is Leo.
- Squeak talks in a high-pitched, squeaky voice, hence his name.
- He is also one of the very few known experiments that can speak English rather fluently.
- Squeak's pod color is red.
- Squeak is one of the few experiments to not appear in the group photo at the end of Leroy & Stitch.
- In the anime episode "Experiment-A-Palooza", Squeak mentions Lilo and that she had given him his name, but he prefers to be called by his number.