One I can't stop using, even after all these decades, is cool. But that 
is cool, Auntie - or at least it is over this side of the Pond, where 60s phrases and outfits (saw my 16-y-o cousin in a distinctly Mary Quant hat/outfit the other day) are coming right back in.
My 5-y-o son and 3-y-o daughter are already describing things as 
cool, so I expect the term will become such a natural part of their vocabulary they'll have to find another one when they hit their teens. 

Another Carnaby Street special is 
Fab. Two years ago I would have felt a complete pillock saying something was "Fab". Now it's close to my favourite expression of approval, and I haven't yet been laughed at for using it  (at least not to my face 

). This might just be a regional thing - I live fairly close to (liberal) Brighton right in the Saath of England, so opinions of those in the frozen North would be interesting here. 
Hi Rhub and dode! 
