Okay, I have a new pet peeve. No, wait, this isn't new, but it is definitely a growing one.
Said pet peeve is when someone brings a laptop into a meeting and taps away on it all during the meeting, ignoring the meeting happening around him. Said tapping is worse when said "him" is a junior developer who needs to hear what is being said in said meeting.
If you attend a meeting, pay attention. If you're not going to or are unable to pay attention, don't come to the meeting. If the meeting is important, but you are dealing with an emergency, let the rest of the people in the meeting know what's going on ("I recognize this meeting is important, but I have 17 people waiting for this hotfix, so I'm going to push it live, and might be distracted briefly, here, wait, let me step outside to finish it."). Don't (DO NOT) spend the meeting working on something else that can wait the f---ing 30 minutes. You aren't going to magically figure out how to embed that f---ing graph while distracted in a meeting you need to be paying attention to what's being said, so f---ing stop trying and pay attention.
I've actually closed the laptops of people sitting next to me in meetings. If you need the laptop to take notes, let everyone know that's what you're doing. Otherwise, leave the thing at your desk.