I noticed theres a new acheivement called green hat
and it says i have a green hat and im proud of it, but it doesnt say how to get it

can i get some help?

It may be that, or when you actually have the little green hat on your avatar.

Edit: Owned by 2 people. Many people have the green hat item. Yeah, I guess it is the avatar thingy.

how do you get the avatar thing?

I think that you could have gotten that in an event of some sort.

When an announcement is posted by a mod at the top of a forum their user title is posted too.
Green hat avatar overlays are done using a nasty user title hack.
This new layer was leaking down over the announcement on several forum announcements in cases where local mods had green hats.
Initially to solve the problem sir (I think it was, not important anyway) removed their green hat overlay to stop the leaking but to stop butthurt because they costed a lot of tc he made a new little achievement thingy for them.
Then it turned out usertitles can be disabled in announcements so he did that, added the hats back and the achievement remained.

And there you have it.