我为你做不出轨的小火车我为你做不劈腿的美人鱼
[wŏ wéi nĭ zuò bù chū guĭ de xiăo huŏ chē wŏ wéi nĭ zuò bù pī tuĭ de mĕi rén yú]
'I’ll Be Your Faithful Train and Faithful Mermaid' means that the user wishes to remain loyal and faithful ('does not betray' or '出轨/劈腿') in their relationship, no matter what the situation is, similar to the metaphorical faithful train and mermaid which will never betray each other. This shows a steadfast commitment to a romantic partner, emphasizing exclusivity and loyalty.