Someone adding you who doesn't know who you are is definitely a peeve, especially when they are from a different country and start asking you if you go to their local state school.
Bigger peeve probably is when some near-illiterate person pseudo-aggressively tells you to say something when they "invite their mate in". Someone once told me to say to his girlfriend she was fat, for reasons i can't even remember. When i declined, the window-scrolling commenced. The things we have to endure to use a software that never fails or "cannot sign you in because the service is 'busy'"