Sanders is the director of Lilo & Stitch as well as the guy who created Stitch, and became the voice of him. He told Mike D that it was a voice he used to use to call people and annoy them. Originally, Sanders and his co-director Dean didn't plan on Stitch speaking. They treated him as if he would be a character like Dumbo. Then they realized he needed to talk and have a very important line at the end of the film. That's when Dean suggested Sanders be the voice of Stitch. He was concerned he couldn't pull it off, but then asked Dean to direct him as if he were an actor and it worked.
While on the podcast, Mike D has a great impression of stitch. He told himself if he ever had Sanders on the podcast, then he would share his impression. Mike D kept his word and Sanders was impressed saying it was really good.