@Nifflas I love this kind of task. A couple weeks ago I did some paid(!) game design consulting work where I just helped brainstorm categories. Just, like, as wide a variety of categories as I could think of.
Harmony Joy Bus Ride
Peachy
Shiny
Bang up
Bang up to the elephant
Corker
Smashing
Fab
Gnarly
Gnar-gnar
Radical
Hellacious
In the pocket
Five-by-five
Beastly
Crushing it
Fetch
Groovy
Legit
Monstrous
Sick
Nanty Narking
Bravo Zulu
High-technical
Five star
Hundo-p
Top marks
Double plus good