or "ghosters" just saw Fnatic Wetdream say it on his stream and just wondered what it meant... any one know?

When an enemy in the game watches the stream to gain an advantage.

People watching wetdream's stream while playing against him to predict where he is and see if he's ganking or anything and acting in consequence of that.

Ghosting?
Isn't that like... using summoner ghost?
[ignore this ignorant post of ignorance]

What the first guy said

"Ghosting" is when you wait for an unsuspecting stranger to pass by and then immediately follow as closely as you can, matching gait, without them noticing you. Of course, you probably wanted something LoL related...

thats what people do to overconfident streamers who dont set delay in their streams. xD

Watching/listening streamers stream when you're playing aganist him. Doing that to gain edge aganist them to know what they're doing, where they're going and so on.

Edit: Lol ninaj'd so hard

it means that someone watches stream of other guy who is on enemy team and see his movements/wards placement/incoming ganks/positions

Ghosting is when a man and a woman love eachother very much and the man invites two of his friends around so they can all insert their *****es in the womans mouth, ****** and **** at the same time, hence the term "ghosting".