This achievement is EASILY earned in the first world "Jibberish Jungle" on the 7th level "Over the Rainbow." This level only consists of the Electoons that you've freed and the yellow lums waiting to be collected. There aren't any enemies in this level so majority of player will have earned this achievement on this level. Upon finishing the level you will earn the achievement worth 15G!
The video is of me also earning the achievement in a whole different way, and unexpectedly.