the let's go guy is a pondering type of person who always extensively thinks about how to respond to a plan, but ultimately will always respond with the phrase 'let's go'.
ME: dude, how about we go to the city center and grab some food at the MAC?
Let's go guy: *thinking extensively about a correct response* let's go let's go!
ME: guys, let's go party tonight!
Friend: sounds like a plan!
let's go guy: let's go let's go!