What does ref mean in slang?

Excuse me, I couldn't help but notice that you just used the term "ref" in a conversation. I'm a bit out of the loop when it comes to slang these days, so I'm curious to know what does "ref" mean in that context? Is it a shortened version of a longer phrase, or does it have a specific meaning all its own? Could you please enlighten me? I'd really appreciate it if you could take a moment to explain.