In case you don’t know or haven’t yet figured it out, echolalia is when a child repeats or echoes back something that is said. When they do it for an extended dialog, like memorizing all the lines from their favorite show, it's called scripting. Then, you add in perseverative behavior (an obsessive interest in something; in this case, repeating something over and over) and it feels like it’s frying my brain one cell at a time. They love it.
I’ve heard practically every single cartoon I’ve ever seen with my children repeated back to me in some fashion. Often they are able to pull phrases and words from various shows they’ve seen and string parts of them all together to form an in-context conversation. Most people who don’t really know my boys may have no idea whatsoever that the words they speak may not even be their own. It’s a finely crafted facsimile of a conversation and it’s an astonishing feat when you think about it. I could never do that in a million years! The way my boys can categorize and memorize information is beyond my comprehension, and is most certainly one of the gifts that comes with their particular brand of autism.