The Child Tracker is a device that Sharon and Randy Marsh buy for Stan to wear at all times in the Season Six episode "Child Abduction is Not Funny".
Background[]
After the excessive number of news reports on child abduction cases, the parents of South Park become overprotective of their children and put limitations on their freedom and privacy to make sure they are safe at all times. Sharon and Randy have given into the hysteria and buy a Child Tracker for Stan to put over his head so his parents are alerted of his whereabouts at all times. At the Bus Stop, Cartman Kyle, and Tweek are also wearing Child Trackers at their parents' requests.