Experiment 533 was the 533rd genetic experiment created by Jumba with Hämsterviel's funding. He was designed to immobilize enemies by flying them like kites. 533 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. Against statistically unlikely (but not impossible) odds, several experiment pods landed in one location: Mrs. Hasagawa's yard, 533's pod being one of them.
At an unknown point, Mrs. Hasagawa mistook 533's pod for an apricot and placed it in a colander for later consumption along with numerous other pods.
After Lilo and Stitch redecorated Mrs. Hasagawa's front yard without her permission, she was less than thrilled with the results, but decided to thank them for their hard work with the "apricots." The pods were then revealed, but before Lilo and Stitch could stop her, she washed them with a watering can, thus activating the experiments.
After he was activated, 533 began to carry out his primary function by attempting to blow away Mrs. Hasagawa's shirt which had been hanging on a clothesline. However, Stitch quickly tied the clothesline to the pole with a strong knot, leaving 533 to blow at it in vain. Later, while Lilo, Stitch, Jumba, and Pleakley were capturing all the experiments that Mrs. Hasagawa kept as pets, believing them to be a danger to her, she saw 533 as another stray cat and started petting him, only to get blown away herself. Fortunately, Lilo made a makeshift lasso out of 521's wrapping and anchored Mrs. Hasagawa, who was then slowly reeled in. When she was safely on the ground, Stitch captured 533 in a container.
533 and the other experiments were about to be taken away, but were returned to Mrs. Hasagawa when Lilo and Stitch saw how much she cared for them. Soon after, he blew Jumba and Pleakley aloft like kites, much to Stitch's amusement, with the two aliens each trying to convince the other to fly higher due to being made extra polite by Experiment 358. 533 was then named Blowhard.
The first 624 experiments, including Blowhard, 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.
Blowhard participated in the following battle between the experiments and the Leroy clones probably by flying attacking Leroys like kites.
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.
- In "Woops", Blowhard erroneously appeared with Gantu's other captive experiments, although he is barely seen behind Felix, even though he was captured by Lilo and Stitch.
- Blowhard's pod color is blue.
- Blowhard is described by the experiment computer screen as, "Experiment 533. Primary function: Big blowhard."
- Blowhard is one of the few experiments to not appear in the group photo at the end of Leroy & Stitch.