A combination of something being Sick (really dope) and Nasty (really stylie). Used in the Ski and Snowboard community to describe something someone did that was mind blowing.
Damn, You see Warner huck that cliff, that was soooo sicknasty!
sick nasty. noun ; slang word used by people who are wayy hardcore, having nothing better to do with their lives then yell at wangsters, spend minutes just listening to stacy's mom in PacSun.
emotot 1: "Dudeeeee. That band shirt is SICKNASTYYY"
emotot 2: "Fer sher. Lets go get moolattes, mkk?"
emotot 1: " ROFLCOPTER! "
"omg brandon got laid, and him and sabrina videotaped it. ugh her ussy is funky and is shitty as hell. uhh nasty. but dieter totally got caught in her office watching it...doode that shit was sicknasty"