"Bad" can mean lousy, or "bad" can mean "good." It's slang, though it seems to be coming into common usage as my generation grows up and passes this usage to our progeny.

Dude, that is soooo 1999. Bad-a** is quite common though. A few others now are sweet, money and the ever-popular awesome and cool. A long, drawn out "sh*t" has many uses now, including indicating that you're impressed with some thing.

Ex. "Sh***t, that sweet new game is so money!" But of course, you can't articulate it.

We weren't talking about this though were we . . . .