REF???!!???

Ref could mean Referral, Refined, or other things. Context?

Referral links probably. They are prohibited.

Refined Metal?

Where do you see it? If it's on the trade forum, it means refined metal. Otherwise it might mean referral as well.

If in refference to trading, it's probably refined metal in TF2, if not, probably a referral link. Either way, welcome.

While you're at it, Please read the FAQ and guidelines. Another nifty tool is the search bar right under the new discussion button that allows you to search for questions already asked . If you want to have some fun comment formatting is here. Here are some good threads as well.

Referal Links probably. Those links that you give people and if they do something you get shit.

Depending on the context, probably Team Fortress 2 refined metal, used for crafting...it's often used as a currency.
Otherwise, it could be a referral link, which is a link posted in the forums that confers some benefit to the poster when followed. Posting such links is strictly against the rules and will get you suspended.

Oh yeah Refined metal okay! Thanks you guys saved me some trouble. lol

People before said the meanings, but don't hesitate in asking things you don't know, nobody born knowing everything.