To be good, in a state of being good, to be having a good time.
(See Firefly)

(interjection) cool, nifty, awesome, pretty, amazing, wonderful, great, remarkable... etc.

Shiny - good in any way, shape or form.

Anything good.

Something or someone that is good, awesome, wonderful, amazing. (See all other positive synonyms.)

This is used to describe something that's very cool

Used by fans of the TV (short lived) show Firefly, to describe an idea/something that one likes (instead of saying brilliant, awesome, cool, neat, rad...?).

Shiny is used especially if the idea or thing is new or bright. Not used so much to describe old things or things that look old.