An expression used in a moment of fascination, surprise, happiness, excitement, hype and agreement. Basically used to express whatever one is feeling at the moment.
It is a vibe.
Some may call it a movement.
It can also be used as call and response for greetings, motivation/ginger.
Emily has just left chorus again for the 15th time and will likely be gone for 48 minutes. Emily 2 looks around and at a complete loss for words, yells "Shabadagaka!!!"