It goes back to at least 1914, actually:
Negative words: Lame, weak
A few years ago, an NPR news story about teen slang told us that “stupid” was an adverb, meaning “extremely;” “dope” meant “good.” That was the first time I had ever heard that “stupid dope” was a compliment. :rolleyes:
23 Skidoo (From the teens or twenties I believe)
Snazzy (forties and fifties)
Well, how about dope? I remember that from at least late 80s early 90s.
Gotcha some dope threads, yo (best when said by dumb white kids).
Sorry, AskNott, didn’t see your post. I never heard “stupid dope” though.
Jake for “good” or “fine” (and possibly, by extension, “cool,” is a lot older than 1914.
From the 1858 Gold Rush in British Columbia’s Cariboo: the Wake Up Jake Saloon.
It’s still in business, by the way.
1990s “Frosty” tried real hard but just never got very far
Late 70s’ “Mint” had currency in the Seattle area
“Cool” has been around for a long time.
There’s also “the cat’s ass”, and how that got to be a synonym for cool is beyond me.
From the 1940’s, check out the lyrics to A Zoot Suit.
Additional lyrics include the words “sharp,” “keen,” “hip,” and some odd rhyming adjectives.
From the late 19th century.
Tony.
Eg
“That Fellow dresses awful Tony for a rube”
I just thought of something
“macaroni” was an 18th C. slang for posh/high end
“yankee doodle…stuck a feather in his cap and called it macaroni”
was the Brits’ way of saying Americans were so dumb/backward/yokel-esque that they’d think a simple feather in a simple cap was all that’s needed to pass for well-to-do
(all through grade school, and I’m sure I’m not alone, I thought YD was an idiot thinking that a feather was a noodle)
Good point. Ahhhh, the nuances of language. 
When I was in high school, we only used “dope” in a kind of sarcastic joking way - the same way we’d use “rad” or “groovy” or “the shizzle”, in a these-words-are-so-uncool-they’re-cool way. Or a we’re-so-white-and-from-the-surburbs way. So I don’t know when people were seriously using it to mean “cool” or “good.”
I still use “awesome!”. I’m a nerd.
I still use “groovy”!
And if something was really keen, it was peachy keen!
I’ve read that local NYC lore has it that the juxtaposition of the Flat Iron Building building and Madison Square Park across Broadway made a wind-tunnel that lifted women’s skirts and exposed their ankles. The expression “23 skidoo” supposedly originated when the police used it to disperse the men who gathered on 23rd to enjoy “the view.”
Dolores Reborn mentioned “far out.” That was one of my favorites. I wish it would return the way “cool” did. “Far out” was in during the 1960’s and 1970’s.
For me the ultimate negative word was bummer.
You almost needed to add “man” to both of these for them to sound right.
“Far out, man!” “Bummer, man.”
“Far Out”
Ah, no one yet has mentioned “pimp”. That makes me happy, for I get to contribute it.
“Pimp” has recently (at least, I think it was recent) been commisioned as an adjective that expresses positive evaluation of whatever it is predicated upon.
e.g.:
“Hey man, that’s a real pimp jacket!”
or
“I’m having a party tonight. It’s gonna be pimp!”
I remember my classmates in the 80’s saying “Ace!” a lot. Perhaps that one was limited to my school?
In Ireland, most particularly in Dublin it’s (f***ing) deadly and has been for ages.