"Kid A" is a soundtrack (and also the full album name) by the English (and English speaking) group called https://en.wikipedia.org/wiki/Radiohead.

"Kid_A" is so popular (even with the pitchy voice, where you can not hear the words clearly even though they're adults, a voice that sounds like mental problems) that it redirects on Wikipedia directly to their Radiohead listing, there are zero other references for the term/variable "Kid A", it was defined as a word (equal to any other major encyclopedia word) by Radiohead.