Nothing like the use of tell-tale slang to pinpoint a person's age and get a reasonably accurate idea of his/her native whereabouts.
It dates the speaker because it generally ages fast. There are many exceptions, of course. (I wonder when someone will come up with an alternative for "tía" in Spain - it's been in use for over two decades by now...)
It also helps to place you because it tends to be a local phenomenon. This is obviously changing with globalization.
Sometimes, it's a new word or expression that catches on - other times, an existing word or expression put to a different use.
In the slang of the 20s, something considered excellent or outstanding or special was "The bee's knees" or "the cat's whiskers"
In the 40s, "cool" took over (with an added ingredient of sophistication, fashion)
In the 60's it was "groovy" or - more drug-oriented: "mind-blowing"
In the 80's it was "gnarly" meaning very cool
but cool was and is still around.
So far, in the 00s "sweet" is supposed to be beyond cool, but I think the word "awesome" is far more extended. (spoken out with half-closed eyes and a long awww sound).
Needless to say, the meaning is no longer restricted to the definition of "a mixed emotion of reverence or respect and wonder inspired by genious or great beauty or sublimity". Its meaning stripped of all pomp and circumstance during the 80's, (I think) it is now used as a synonym of great, cool, beautiful, excellent, outstanding, terrible, dreadful - you name it. And it looks as if it's here to stay.
Since these days anything slightly above average is considered outstanding, you get a chance of using the word repeatedly. The number of words you can save on in this manner is awesome.
Should you come across something a little more striking than average, you can always resort to "That's absolutely AAWWWSOME" (this time with "eyes wide shut").