으라차차 is originally a shout to muster up one's strength, and can also be a word showing approval and support, somewhat similar to "Hurrah!" in English. Imagine a player in a lifting competition. When they try to muster their strength to lift the weight, they might shout this phrase. It doesn't really have any meaning other than projecting energy, power, positivity, etc. So 으라차차 와이키키 might be translated to "Hurrah, Waikiki", "Go, Waikiki", "High five, Waikiki", or something similar.

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