Completely and utterly unmatched in uniquesness, cooless, and fabulousness. It's like "baller" but more extreme. Usually used in instances of extreme excitement and enthusiasm.
"You hitchhiked to California, rode a donkey to the ocean, surfed a tidal wave all the way to Hawaii, met Obama’s second cousin and beat Scott Hamilton in the first annual Lite Rock on Ice competition, ALL IN ONE DAY?! That’s Sick Baller!"
"We have the most sick baller fort in our living room - you have to come see it."
"James' APA project is totally sick baller."