What's with the name of this dish? Is that what you're thinking? Well, even if you aren't, I'll tell you about it anyway.
And here's what I can tell you: I have no flippin' clue.
Interviews with my Thai friends and family members have yielded various conjectures regarding the origin of this dish's name. They range from the laughably absurd to the yeah-maybe-but-nahh.
But the conclusion is that nobody knows. True, it's probably unfair for me to base this conclusion on a small sample of people whose intelligence may be called into question based solely on the fact that they either share my genes or consider me a friend. But, really, I doubt anyone else is any more or less clueless about this name issue than these people.
Out of all the conjectures, two stand out as the most plausible. Okay, fine. They're not the most plausible; I just like them more than the rest.
One theory maintains that the golden color of the hard-boiled eggs have been deep-fried and thoroughly doused in a deep golden colored sauce. With the Thai culture being quite entrenched in symbolism, it's not beyond the realm of possibility that the golden color, which reminds one of actual gold, is linked to wealth, something the parents of a woman naturally hope for in their future son-in-law.
It's actually the other theory that I really like. It paints a much grimmer, or shall I say more gruesome, picture. But that's precisely what makes it appealing. The Thai word for "egg" (as in the kind of egg laid by the female of various species) is the same as the word for the, uh, male reproductive glands that come in pairs.
Now visualize an egg—and we're going to be ambiguous as to where exactly in the semantic range of the word this occurrence of "egg" falls—being boiled, deep-fried until blistered and browned all over, whacked in half with a cleaver or methodically and slowly sliced open with a sharp chef's knife (possibly with the slicer laughing maniacally while slicing), then having a sticky sauce poured on top of it in the manner of hot melted asphalt on the surface of your new driveway.
"Here's what's going to happen to you, boy, if you mistreat our daughter," seems to be the message that the parents of a woman want to send their future son-in-law. If the guy doesn't run away in terror, with his hands covering the part where his pant inseams meet, then I guess that guy is considered worthy of the daughter.
All you really need to know is that son-in-law eggs are very loved by the Thai people. It's one of those down-home dishes you don't usually find at fancy restaurants in Thailand; you find them mostly at no-frills rice-curry shops or school cafeterias. For sure, you hardly ever find them at a Thai restaurant in North America.
It's a dish worth trying or at least being familiar with, for it captures so very well the sour, salty, sweet flavors associated with traditional Thai food without the burning heat that is often mistaken as the necessary component of "authentic" Thai cuisine.
If you have some leftover hard-boiled eggs from this past weekend and you've run out of fresh ideas on how to use them, make son-in-law eggs. Clarity on the origin of the name is not a prerequisite to enjoying this classic Thai dish.