I don't have my hard copy here and Google is failing me but this is addressed by Terry Pratchett in (I think) Only You Can Save Mankind.
The context is some teen-agers talking about how it's not cool to say Yo, or Crucial, or Well Wicked, but Cool is always cool.
Would appreciate the full quote if somebody can find!
'It's not cool to say Yo any more,' said Wobbler.
'Is it rad to say cool?' said Johnny.
'Cool's always cool. And no-one says rad any more, either.'
Wobbler looked around conspiratorially and then fished a package from his bag.
'This is cool. Have a go at this.'
'What is it?' said Johnny.
...
'Yes. We call him Yo-less because he's not cool.'
'Anti-cool's quite cool too.'
'Is it? I didn't know that. Is it still cool to say "well wicked"?'
'Johnny! It was never cool to say "well wicked".'
'How about "vode"?'
'Vode's cool.'
'I just made it up.'
The capsule drifted onwards.
'No reason why it can't be cool, though.'