It's a slice-of-life story. Gay Chinese guy wants to come out over his traditional sister's objections. This becomes a running battle at the family Christmas dinner. The big reveal is that while brother and sister were fighting in the kitchen the guy's boyfriend had been told, "Oh, don't call us Mr. and Mrs. Ho, call us (the Chinese words for father-in-law and mother-in-law)." So it ends happily except for the sister.
A good, classic, well-done coming-out story, fit for any literary magazine. I wouldn't bat an eye at finding it in the New Yorker.
So what does the title mean, and why is this in the Hugo nominations? "The Water That Falls on You from Nowhere" is literal--the world has magically changed so that anyone telling a lie has water fall on them. Amount of water depends on the severity of the lie. Okay, that makes it a fantasy story, modern setting, one impossible thing. Good start for an SF/F story. This magical lie detection turns the story into . . . well, it doesn't affect the story at all. No lies are revealed that people wouldn't know from facial expressions, body language, and pre-existing knowledge. There's no surprises coming from it.
Which is boggling, when you think about it. Revealing all lies? That would shake every part of society. Politics and law enforcement are obvious. But it's going to affect everyone. High school girls turning down dates. Bosses asking for "voluntary" overtime. Marital disputes. This would be world-changing. But none of this shows up in the story.
There are great stories in that concept. My favorite is Spider Robinson's "Satan's Children" where the heroes use a new drug to force a few score people to be honest as a test before deciding whether to release the drug to the world. There's another on the subject in this year's nominations, “The Truth of Fact, the Truth of Feeling”, by Ted Chiang (my current favorite of the stories I hadn't read before getting the voter packet). It examines the impact of a new technology that confronts people with the lies they've told themselves, remembering old disputes with themselves in the right.
But there's none of that in "The Water That Falls on You from Nowhere" even though the writer displays enough skill to tackle the issue. Instead it's a mundane story with a bit of window-dressing to sell it as SF. That was enough for 45 or so people to nominate it, but I'm ranking it as No Award.