Oh, you’re fancy now? Fine. If you’re in Hong Kong or talking to your friend’s cool grandma, use 新年快樂 (san nin faai lok) and 恭喜發財 (gung hei faat choi). It’s like Mandarin but with more swagger. Almost identical, but the tones are different enough to impress.
Fun fact: Cantonese speakers love when foreigners try. You’ll get a pat on the back and probably free food. Don’t question it—just eat the food.