Extremely unliked person who at any chance of social interaction does not succeed. Usually found persistantly following a group of people whom strongly dislike him/her. Has few positive aspects of their personality. The term is generally used unreasonabely and excessively in a wide range of situations.

when a person pops into the view of a camera behind the original subjects of the picture at the last second, often so only a portion of their face is showing

To be present at an event or browse social media with more effort than most without being noticed. Ever. This can count lurkers from Twitch.Tv and other websites the stream videos, not necessarily live ones. These people usually get famous.

A lurky person, someone who just stands out and creeps on you, doesnt look like you would ever talk to them

someone who is stealthy and ninja-like. observes others for future reference.

To get in, and effectively ruin, someone else's photo. Can be whole body lurkage, or merely two fingers. Practiced by Bubbah in Germany.

To stalk someone, or follow them suspiciously, in a lovestruck or obsessive manner.