If you’re hooked on something or just hooked, it means that you’re addicted to something and you can’t get enough. You can be hooked on chocolate, basketball, a new TV show or something more dangerous like smoking (which is not cool by the way!)       

Example 1)

“What did you think about the new sitcom with James Franco?”

“Loved it. I’m hooked already!”

Example 2)

“I miss George!”

“George’s your ex. You’re hooked on him and it’s not healthy. It’s time to move on!”