Polly, A.K.A. Experiment 395, is an illegal genetic experiment created by Jumba Jookiba. He is designed to make targets repeat themselves three times. (does so by using telepathy to make his targets repeat an action or spoken word three times without them realizing that they have done anything out of the ordinary). His one true place is working in Hollywood helping actors to remember/rehearse their lines.
Experiment 395 was the 395th genetic experiment created by Jumba with Hämsterviel's funding. He was designed to make targets repeat themselves three times.
395 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 the unknown point, he was activated, captured, tamed and named Polly.
The thing that the target repeats is the last thing that they did / said before experiment 395 uses his power on them.
The effects of this experiment wear off when the target becomes aware of the repetition.