I ran into the following wordplay:
That's your dad! [...] I heard he has two wives, one back in the countryside,
and a new one. Why do you think one's called Sitian and the other is called Yiku?
I did some research on Google and found this idiom: 忆苦思甜。I thought this was somewhat relevant here, but I'm still having a hard time understanding the joke. How would you render it in English?