“Cool and groovy” has been a favourite of mine for over a decade now.
(I had to abandon ‘mint’ for being too local even within the UK 
)
Did “cool” ever become uncool?
I am in for sure on this kick. Ninja Pleeeeease!
Me too. Swing you cats!
On the other hand, I found '80s Valley slang annoying, and think that modern '90s/'00s slang irriating to an extreme. Part of it is the ghettospeak that is immediately co-opted by the most uptight, square-assed people on the planet, and the other part is the unimaginative overuse of certain phrases as all parts of grammer, the biggest offenders being “like” and “f**k”. And I’m tired of hearing how everything “smells like ass”. I have a cow-orker that calls everyone he doesn’t like an “ass-munch”. If he’d just vary it a little bit–maybe “ass-clown”, “butt-biter”, “hole monkey”, something–it wouldn’t be so grating. But everything is “ass munch”.
There’s just no cleverness in modern dialog. There probably wasn’t back in the day, either, but since my point of reference is mostly based upon film noir with crisp dialog and snappy comebacks to every line, I like to imagine that it was better. I want my my life’s screenplay to be jointly written by David Mamet, Robert Towne, and David Webb Peoples, directed by Terry Gilliam, and produced by Robert Evens.
Oh, and I want Julianne Moore or Michelle Yeoh to be my co-star. How hard could that be?
Stranger
Just yesterday I used “He’s dead Jim” to indicate that something wasn’t going to work out the way we wanted. I was told I was dating myself.
I still use ‘Dude’ in all seriousness. It’s a dead useful word, it is. Oh, and I’ll be like, “Hey, man.” 
Duuuuuuuuuuude. Dude, dude, dude. Dude?
Dude.
I still say far out sometimes. Or heavy, if something warrants it. Don’t see too much that’s heavy these days. I never got into calling anyone “dude” except in jest.
I’m student teaching in a middle school (my content area is ELA) & I’ll use expressions like “cool”, “dig” (as in, “So you have to give me three metaphors that’re used in the story. Dig?”), “chill/chill out”, and “rockin’”.
They find it particularly amusing when I ask them if they “dig”.
I still use cool and “my bad”.
Gah. I forgot: I also use “dude” on a semi-regular basis. I’m 26, FYI.
Sorry, but yes. A long time ago. It just doesn’t feel comfortable anymore, in the same way “rad” just doesn’t feel right. I don’t hear it too much anymore, except from my mom from time to time. YMMV.
Some I can’t part with:
Dude
Sweet
chillin’
po-po
ho
hoochie-mama
what’s crackin/cracka-lackin’?
chron
let’s bounce
pimp
killed (as in “who killed the pizza?”)
for real
fa shizzle
geeked
ghetto
holla (that’s usually just for fun though)
hot
nookie
poser
straight
thug
poot
throw down
cluster fuck
jacked up
uhh, yeah I use a lot of slang. Mostly in casual conversation, sometimes one will slip out at inappropriate times. Ah well.
Worth mentioning, but never used: shit a cold purple twinkie
Dude, that’s totally awesome. I still use all the same cool slang I would have used back in the day.
“Aaaaaaah… shut yer pie-hole! Or I’ll paste you right in the puss.”
Often spoken by me to whiny teenagers.
Often ignored by whiny teenagers.
For me, if I go play pool, it’ s not fun, it’s “a gas”. If I don’t like something, it’s not “not my thing”. It’s “not my bag”.
Sadly, that’s my problem with the post-Friends corporate-sitcom: it’s call-&-response, with every retort being a (supposedly) snappy comeback.
Oh, and I use “broad” and “groovy”.
Yesterday in the office I said to a colleague (who’s at least 20 years younger than I): “I’ll bet you London to a brick that…”
She had no idea what I meant. I realised that it’s probably an older slang term that she had never heard before.
Just a few minutes ago I told my sister I had to clean out my snot locker.
Sometimes I’ll say ‘Ah, banana oil!’, which I picked up from the übercool The Forbidden Zone.
And, occasionally, I’ll say Farkin’ far out. (I think that one dates from the '70s.)
In high school things were outraaaaaaaageous, though sometimes people used the older righteous. Both mean ‘really good’. I never use those now.
Fuckin’ A!!