Heard this song and thought of this thread.... I want to say the current phrasing of 'let's go' gained popularity after that chris brown song, 'look at me now' in 2011...
He says 'lee'goo' in the beginning of the highly popular song.. Also notable that's when lil wayne started skating heavy and says 'got money on my radar, dressed like a skater' in the song at the height of lil wayne craze.
Part of my reasoning for that being that I worked in a highschool around that time and remember every kid saying that phrase and hearing it morph to grammatically correct but louder... 'LET'SSS GOOOO'
Not sure any other reference of 'let's go' mentioned in this thread line up with the current status of LETTTSSSGOOOO
"look at me now... look at me now... im gittiin pay-perr."