Collect 100 nuts
Collect 500 Nuts
Collect 10000 Nuts
Collect 10 stars
Collect 100 stars
Finish Stage I
Burst into flames more than 10 times
Use O2 as jetpack fuel for more than 5 consecutive seconds
Max out an upgrade
Complete Stage IV
Finish the game...Like, for real.
Unlock every suit (and then go flaunt it).
Finish every level with 3 stars