Haha, thank you!

(By the way, the joke was still funny after the explanation, that's quite rare.) :)

It made me think too, but I still don't get it!

That's without mentioning the day of the week, of course.

Chance of having two boys: 50% * 50% = 25%
Chance of having two girls: 50% * 50% = 25%
Chance of having a boy and a girl: The remaining 50%

He can't have two girls, so that's 1/3 chance he has two boys and 2/3 chance he has a boy and a girl.

Alright, I will try rephrasing it then:

John has exactly two children. At least one of them is a boy who's born on a Tuesday. What are the odds that John has two boys?

So if a man comes up to you on the street and says: "I have two children. At least one of them is a boy. What are the odds that I have two boys?", you'll go:

Well, you can have (boy, boy), (boy, girl) or (girl, boy). But we should count (boy, boy) twice, so that means there's 2/4 = 50% chance that you have two boys.

Of course there isn't!

Here's another example: What are the odds of getting two sixes when rolling two dice? Well, most people would say 1/36, but then we're only counting (6, 6) once. You would say we should count that twice and so the odds are 2/36. This is completely wrong.

If a man comes up to you on the street and asks you the question about having two children, at least of them being a boy who's born on a Tuesday, it doesn't matter if he does have two sons who are born on Tuesdays. It's still just one man. You wouldn't count him a hundred times in your statistics if he had a hundred boys, at least I hope you wouldn't.

Surely you can't be serious.

It's still OR, not XOR. :)

There, go ahead and count. There are 27 possible families when where the man has (at least) one son who's born on a Tuesday. You can then easily see that there are 13 cases where the man has two sons.

"You can visit him if you or your girlfriend knows where he lives."
"Goddammit, we both know, so now we can't visit him!"

Why not just start with 3 then? :)

Correct, otherwise there would be no "spooky action at a distance", as Einstein put it.

A lot of people explain it like this: You write two notes, one has the letter A on it, the other has the letter B on it. Then you put them in envelopes and mail them to two different people. When one of them gets the envelope, they instantly know what the other person got.

This explanation is incorrect, because there is no letter A or B until either is observed with quantum entanglement.

A better explanation would be: You put two pieces of magic paper in envelopes, without looking at them, and mail them to two different people. When the first person opens their envelope and looks at the note, it will switch from random to display either the letter A or the letter B. The instant it does, it magically instantly tells the other piece of paper to show the other letter. It really does transfer its state faster than the speed of light, we just can't use it to transfer information faster than the speed of light.

So if I kill someone in their house and leave no evidence behind, I'm not guilty? Of course I am, even if it's not possible to prove it.

I agree. I salute them for their courage and I applaud their perseverance and I embrace them for their faith in the face of adversarial forces.

That makes sense, thank you, and that goes for everyone else who has posted insightful answers as well. :)

I really wasn't trolling, some people have just been arguing that Apple really doesn't want other ways to access applications than through the app store. (There was something about a C64 emulator being removed as well.)

So I just didn't understand why HTML5 was OK then, when it gives at least some of the same possibilities.

So again, thank you for your time everyone. :)