A child that grew up playing with a amazon kindle instead of the much superior apple ipad.
Coworker 1: "Did you hear that coworker 3 was a kindle kid?"
Coworker 2: "Coworker 3 must've been in special learning classes as a kid,"
Kindle kids is used when someone with a kindle fire has chatted up kids on there kindle fire, so you call the kids kindle kids as they have been captured by a pedo.
Danny stop chatting up your kindle kids