I had this dish at a Thai restaurant on the other day. I was curious the funny name then I asked the waiter why this dish has such funny name called Son-in-law eggs, but he couldn't tell me an answer.
After I google, according to
here, this little deep-fried, savoury egg dish is traditionally cooked by Thai mothers for their soon-to-be son-in-laws as a grave warning that if they decide to get a little promiscuous with their beloved daughters, their precious gems will end up boiled, deep-fried and served with sweet sauce. Thai's mothers are cute and creative right ^_^
This is a great way to get rid of leftover boiled eggs, the sweet and sour pour over fried eggs, kids especially love them.