A punk is a young male street prostitute. So you're calling someone that punk's ass, which is what gets fucked all the time by who knows who, so that's bad.
You: Look at that guy. He can do flips.
Me: I wish i could do that. I can do many things, but not this.
I remember that we found 100 dollars one summer.
You: Next to being a Punk ass, that's the only thing I've ever done.