I'mma fuck you up.
Mitsugoro's intention was to prove his immunity to the poison by ingesting four times the amount that could ordinarily kill a dude.
What He Actually Proved:
Why did he think he was immune? We're guessing he didn't, and was just one of those guy who likes to make shit up at parties. Now, we'll admit it takes balls to run with a lie that can potentially kill you. But Mitsugoro didn't just run with it, he jumped into a sports car and sped off a cliff.
Seven hours after ingesting the four livers, Mitsugoro was dead. According to the Fugu experts at Wikipedia, the victim of the neurotoxin found in fugu liver "remains fully conscious throughout most of the ordeal, but cannot speak or move due to paralysis, and soon also cannot breathe and subsequently asphyxiates."
This means Mitsugoro almost certainly died looking up at several friends pointing and saying they knew he was full of shit and that he should pay up (we're just assuming a bet was made somewhere along the line).
What He Tried to Prove:
That high rise glass is unbreakable, and that the universe has no sense of irony.
Garry Hoy was a lawyer from Toronto, Canada, whose claim to fame is being the punch-line for every single "famous last words" joke ever made. Those last words pertained to how the glass windows of his 24th storey office in the Toronto-Dominion Centre were "unbreakable."
You can see where this is going.
"How can I get the interns to respect me..."
What He Actually Proved:
As you may have guessed (you veritable Sherlock Holmes, you!), Garry tested his little theory by slamming his body up against the glass. He burst through the window and plunged to his death, leaving a group of nervous interns either freaking the hell out, or fervently writing down a "famous last words" joke, depending on how much of a callous asshole they were.
"You hear something?"
What is shocking about this story is that the window gave way on his second attempt. Apparently Garry was unable to rest after having risked his life just one time. We can imagine how the scene went down:
Garry: "These windows are unbreakable, kids!"
Garry: "No really, check this out. Don't try this at home, kids."
[Garry hurls himself at the glass to shocked cries. The glass holds, and raucous applause erupts from the interns.]
Garry: "Hold your applause. I'm not satisfied with having proved the strength of this glass just once."
[Garry's face turns dark.]
Garry: "Let's see what you're really made of, glass."
[Garry gets a 30 foot running start and launches himself, Superman style, through the glass. This time, the window gives way and sends him plunging to his death.]
"Ha ha! Take that, glass! Oh wait. Shit!"
Perhaps the best (or worst, if you value human life) part about this story is that it wasn't actually the glass that broke - the window pane popped out, and is the reason he fell to his death.