@Tom: I agree, everything's always un-green and blah. But if you personally don't give a damn about the environment then why would your reasoning be better than his? "What is it with all these people who care, I don't give a shit! Why doesn't everyone else not give a shit?" is kind of a stoopid thing to say, imo.

"In 1898, fifteen year old etc." 1898? You need to go back 110 years to find the *only* helium-related death? Ok so I suppose it was 1989. Can I get a reference for that other than BASA? No? Neeeext!
"In Australia, Kristi Brash from Victoria had a near death experience when she appeared to freeze and turn blue after inhaling the entire contents of a balloon [...] but luckily regained consciousness after a few minutes. [...] after examination she appeared to be find although any long term affects of the inhalation are yet to be determined." So in short, nothing happened. There is strong evidence that banana peels can be deadly too, you know.

He's got a point.
I mean, he must.

You don't smoke, you don't drink. Can't be too hard to avoid going to a bar. Let bar owners choose if they allow smoking or no, and you just go to the boring places that don't allow it. I don't have that choice when it comes to cars. You've never even thought about people who drive their car for no good reason, laziness not being a good reason. I wonder how many cigarettes to the mile. You get all high and mighty (and extremely boring) about smokers but you don't care about cars. That, to me, is nonsense.

@Abscissa

Sorry, but your rebuke just doesn't make sense. You've been pwned but are too proud to admit it. That's fine.

In front of a traffic light, you're in your car on your way to work. You could've taken public transport but you didn't because, well, you have a car. I pull up next to you on my bike, smoking a cigarette.
Your cost to me & others: noise, pollution, health risks, general traffic danger, congestion
Your cost to yourself: same + stress from congestion
Your benefit to me & others: -100
Your benefit to yourself: public transportation? Otherwise: fine, you need a car.
My cost to you and others: -100 (subtracting your cost #1)
My cost to myself: a lighter wallet, but money's not an issue right now. Cancer? Whatever.
My benefit to you & others: none, except in the negative because my cost is -100
My benefit to myself: I enjoy it.

Conclusion: if you really need a car, you really need a car. I won't bitch about it. You will about my smoking though. Now how is that fair? Looks like you don't even need to smoke to not be able to do a decent cost-benefit analysis.

Who are you calling an idiot? Do you drive a car? If so, you're killing more people *and* ruining the environment with your toxic fumes than I do with my smoking. Do you know the ration between people dying in car accidents versus people dying from smoking? Are cars illegal? Right. I'll probably die in a car accident before I get a chance to develop cancer. Want to get self-righteous about smoking? Sell your car and buy a bike. Idiot.

First off what is your definition of 'the real thing'? Besides the fact that 'reality' is in itself an illusion - but let's not digress, you sound too thick to be acquainted with the subject anyway - calling a diamond 'the real thing' is pretty pathetic. What's less 'real' about a ring with another precious stone in it? Right, nothing. Just 'cuz you're being suckered into thinking that diamonds are 'the real thing' you decide to give them your money. You're a monkey! So much for critical thinking. Second, if you can measure the love for your wife and hers for you in dollars or pounds, you're both really not very interesting specimens.

P.S. proposing by way of a video that starts playing on the screen of the box that you left on her desk, the moment she opens it. Nerdy, yet kind of cool! Easier for her to weasel out of it though.