One of my kids used to use that term about 20 years ago. I took it to mean cool or fashionably acceptable. In the genation previous I believe the term was "mint" and in the generation before that "keen".
Those two I know, but I must be "uncool" to have missed the one mentioned by Goober. If I were an academic, I'd probably use the word "superlative." :lol: Of course I'm not, so basic terms like "sh!t-hot" work for me. :lol::lol: