One of my biggest pet peeves is having people look over my shoulder when I'm working on my computer (e.g. while editing images, writing e-mail, working on a web journal). It's like someone peeking over your shoulder when you are writing or reading a personal letter. I really hate it, and on every trip I take I inevitably have to relate my feelings to others, because personal space on boats is virtually impossible to obtain. On the other hand, I don't mind over-the-shoulder peeking so much if I am just screwing around on the web, or if I am showing/browsing through photos.
And if it's my grandfather peeking over my shoulder, I don't really mind, either.
However, when my mother, grandmother, and grandfather are all simultaneously nagging me about a currently non-existant girlfriend/wife/grandkid/etc. (while peeking over the ol' shoulder), it's almost too much to handle. So I fled, and am now alone in another part of the house.