This past Saturday night, I was at a family event when my two 21 year old nephews were 'catching up' with each other. Early in their conversation, of which I was part, one said to the other, "That's sick." His response, "Definitely." Meanwhile, "older" Aunt Betty and Aunt Kate, both nurses and both in jeopardy of losing their 'cool' status, looked at each other as I asked, "What does that mean? Best not to say something's sick around me and Aunt Kate (also a nurse)."
Their definition explained that something that is "sick" is something that is exceptionally cool. According to many websites, like Urban Dictionary, using "sick" to describe an album, a book, a website, or ANYTHING, can actually be used in two contexts. One would be a complement; one not so much.
Kate and I laughed aloud as we began musing about using the colloquialism in our roles as a nurse. Given the nature of our business, I think we'll stick with phrases that seem less problematic.
Might be a good idea, though, for my vocabulary if I hang more with my nephews. I might learn a few new words.