陪我天涯到海角陪我白头到偕老
[péi wŏ tiān yá dào hăi jiăo péi wŏ bái tóu dào xié lăo]
This nickname conveys a deep yearning for a lasting, lifelong companionship that can go through many places ('to the ends of the earth') and withstand the ravages of time, hoping to be with someone until death do they part.