Definitions include: a computer whose security has been compromised, and is then used to perform computer misdeeds, such as sending spam or performing denial-of-service attacks.
Definitions include: Channels on YouTube who are desperate for subscribers and popularity (just for the sake of popularity), so they'll tell you to like and subscribe to their channel shortly after one of their videos start. If you're a newcomer and only one minute into the video, you'd barely know anything about the channel or its content, so why would you like the video and subscribe to the channel when it tells you to? Thankfully other channels either ask you to like and subscribe at the end of the video, or not at all because they know you're smart enough to do that on your own.