it's like the same thing as saying to the hipster "yeah, right" or "give me a break". It's an urban style way to say "Hipster, Please stop your nonsense".
Hipster: I only listen to music that nobody know. That makes me different from everyone.
Me: Hipsta Please!
meaning hipster ya right or ya your a hipster in a sarcastic way ...also known as being a shirt that harry styles wore ! :)