I Know You Are But When Am I, A.K.A. Experiment 139, is an illegal genetic experiment created by Jumba Jookiba. He is designed to mimic what people say.
Experiment 139 was the 139th genetic experiment created by Jumba with Hämsterviel's funding. He was designed to mimic what people say.
139 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 I Know You Are But What Am I.