Skiing/snowboarding vernacular. A strong adjective for
1: amazingly deep fresh powder snow
2: an insanely awesome line down a step mountain face.
3: A big ballsy jump off a cliff or in a terrain park
4: Anything that is 'off the hook' epic and worthy of such status
An portmanteau of the the popular adjective "sick", a word extensively used in the snow sports community and "tarded" from retarded. Something so good it profoundly affects you .
Did you see the video of Jamie Pierre doing the 77m cliff jump in Wyoming?
...yeah, that was sicktarded!
Did you get out in Hakuba after the epic dump?
....yeah sure did, it was nipple deep and sicktarded, pure sicktarded.