一刹花火
[yī chà huā huŏ]
It refers to 'Flower Fireworks in A Moment' with '一刹'(yí chà) indicating a very short moment and '花火' (huā huǒ) specifically refers to fireworks but generally also means spark or bloom. This nickname can represent ephemeral brilliance or beauty, fleeting pleasure moments or something that is dazzling yet disappears quickly.