Usually a guy who is good at sports, drinking, partying, and pleasing the opposite gender. These guys are a special breed of guy that can only be found in the 951. There is a group of friends who coined themselves as THEE Sick Ass Dudes
person 1: "that guy is badass!"
person 2: "yeah, he's a sick ass dude"
person 1: "oh for reals? No wonder!"
More often than not, it is used in a derogatory manner. Can also be a term of endearment. Personally I mostly say it when someone tells me they did something I have no interest in.
12 step recovery jargon referring to someone new who talks about how great life is, now that they'resober. Usually meaning that the person is out of touch with reality.
The new guy seems pretty happy for a dude who has no job, no money and no family. He must be on a pink cloud.