你说世界末日怎么办俄说世界尽头俄陪你
[nĭ shuō shì jiè mò rì zĕn me bàn é shuō shì jiè jĭn tóu é péi nĭ]
Translating closely as “You said what about the world's end? I'll say I’ll accompany you to the world’s end.” This username signifies loyalty and commitment to stay by another’s side even at times of uncertainty and extremity. It conveys deep affection and promise.