the world keeps popping up and I'm baffled. I've asked before in threads but I never saw an answer.

 

/\ This.

 

I beleive you mean when someone quotes another person and puts "This" as a post. It means they simply agree with the quote.

 

Its a way of agreeing

 

This...

...this...

...aaaaaand this.

 

"This" means this. Sometimes it means that, as stated previous. But in many case "This" means this, and this, and that, and this, and all of that.
You knowswhat I'm saying?

 

It's gay slang, part of a mating ritual. Basically, it means that you are waiting in a bush outside the other person's house, right now, with your trousers down and some lubricant ready applied.

 

This ^^

 

*fires air rifle into bushes outside house*

 

Yep, it's just a statement of complete agreement with the quoted post; it's pretty much the antonym of "fail".

It's also a good way of boosting your post-count without being considered spam, but still only requiring minimal effort.

 

I'm almost tempted to use "this" once more, partly as another throwaway joke and partly because I agree.

...so I'll just say that I agree with your post.

 

^^...That.

 

This ^^

 

This is spam.

 

This.