Sharing your online passwords for an online service like Netflix and HBO Go is now a federal crime, according to a recent court ruling.
According to the U.S. Court of Appeals for the 9th Circuit, a user cannot circumvent a computer system's security measures by "going through the back door and accessing the computer through a third party" per the Computer Fraud and Abuse Act.
It comes from an unrelated case last week involving an employee who left a company with passwords.
Although illegal, it's unlikely you will be prosecuted for letting someone else use your password.