Jesus Christ! If I ever take my family to Yellowstone, dinner the night before we get there is going to be boiled sausages or perhaps lobster.
What I believe you were thinking of was the story as related by Bill Bryson in A Short History of Nearly Everything.
Another big problem, as I understand it, is that some of those pots and pools have delicate structures. The coins punch holes right through them.
Different topic, but at the Anchorage zoo, coin-throwing morons killed off the fur seals because the coins were ingested. During the exhibit closure, zoo folk built a wishing well, with signs in many languages urging people to toss their fucking coins in there, because otherwise animals would be poisoned and die. They eventually restocked the fur seal exhibit and within a few months they were all dead again from. . .wait for it. . .ingesting fucking coins.
I’ve seen coins thrown in pools in caves, at waterfalls, in every conceivable bit of water imaginable. It’s the most idiotic, mindless activity in the entire idiotic tourist mindset.
Bingo. That is exactly correct.
.
Perhaps one day the Lady of the Lake will rise out of the water and shove Excalibur right where it belongs 
“I’m tired of these mother fucking coins in my mother fucking water!”
Unfortunately, Yellowstone hasn’t cornered the market on ‘Natural Wonder Induced Stupidity’. Having worked at Grand Canyon for many years I still marvel how people will ignore safety warnings for a half assed thrill that will leave them maimed or dead. Such as:
Climbing over the railings with signs that say, “Danger! Ledge unstable!” so they can get a picture of a dumbass standing right on the unstable ledge.
Holding onto aforementioned metal railing watching a lightning storm.
Teasing the rattlesnake so it will come out from under the rock for a photo op.
Its 120 degrees at the bottom. Why in the world would you think your 250 lb couch potato ass would hike all the way down and all the way back in less than a day? With 1 bottle of water? In those shoes?
I don’t even want to get started on people who think hiking in slot canyons is fine because the storm is waaaaay over that way. Forget what the Park Ranger said, obviously she must be full of shit to tell people that slot canyons are flash flood zones for storms that are miles away. Its perfectly sunny right above our heads. Is that an earthquake? What is that roaring sound?
I just reread Bryson’s account, which includes the detail “…they backed up a few paces, linked arms and, on the count of three, took a running jump. In fact, it wasn’t the stream at all. It was a boiling pool. In the dark they had lost their bearings. None of the three survived.”
So my memory was accurate, although Bryson goofed about the two survivors. Which I suppose still wouldn’t present quite such a logical problem about where the details came from-- one or more of the geniuses might have survived long enough to tell what had happened.
But I have to admit that I took it for granted that they all must have died on the spot.
.
Bryson has a bit of a reputation for amusing-but-inaccurate writing. A Walk in the Woods has a few such instances though none as glaring.
Errors in SHONE:
0767908171 - Errata and corrigenda
They’d better add the Yellowstone Survivor Count to the list.
Oh man. We were in Badlands National Park on that same trip. For any who may not know, Badlands formations are composed almost entirely of soft sedimentary rock, which erodes and crumbles into unique shapes, spires, etc. It’s unstable, at best. There are signs everywhere cautioning people about this, and yet I watched several 20-somethings walking back along a very narrow promontory, while one of them picked up his girlfriend and started pretending to throw her over the side. :rolleyes: People took the most horrifying chances there, climbing out on unstable areas for the sake of a photo op.
As stated in Snopes, he was talking. Was he aware of his impending death? Sorry but those details are lost from my mind.
After that incident, a number of us were led by an old time ranger on a hike through several thermal areas (off trail). Pointed out were several thermal features containing animal as well as human bones. Not all victims are either identified nor recovered.
I remember visiting Rotorua, a geothermal area in New Zealand when I was a kid. They had a sign next to the boiling mud pools that said “Any person throwing objects in the pools will be required to retrieve them”.