Free cable TV
Before the internet came around, there was a thing called cable TV. Basically, cable TV provided customers with premium channels like Disney Channel and HBO. In order to attract more customers, cable companies would offer free month-long trials. After the trial, if you didn’t subscribe to the service, they’d come back and disconnect your service.
One father realized what was going on. So, a couple of days before his free trial came to a close, he disconnected the cable by himself. The cable company couldn’t tell whether he was a free user or not since his signal wasn’t in the company’s records.