那些快快乐乐的曾经那些幸幸福福的时光
[nèi xiē kuài kuài lè lè de céng jīng nèi xiē xìng xìng fú fú de shí guāng]
It implies a longing for past good times. 'Naei Kuai Le De Ceng Jing Naei Xin Fu De Shi Guang' refers to 'Those happy times, those blissful moments,' evoking nostalgia for carefree and joyous periods in one's life, usually with fondness for days gone by.