This is more intended for intellectual conversation. The Monty Hall Problem is a very simple probability problem that has become famous for how counterintuitive it is. Here it is:
Code:
[A] [B] [C]
Pretend you're on a game show, and the host asks you to pick one of three doors. Behind one of the doors is a brand new car, but behind the other two there are goats. So pick a door (We'll pretend the person picks [B]). Now what are the chances that you picked the car? One in three, correct? Pretty simple so far. Now the host shows you that [A] is a goat. Would you like to switch your choice from [B] to [C]? Normally the person will say "No", so ask "Why not?". They'll believe that now, because there are only two options left, their chances of picking the car are 50/50; but they're wrong. Actually, by switching their choice, their probability of choosing the car will double from 1/3 to 2/3. This is because when they picked the door, their chances were 2 out of three for picking a goat. So they PROBABLY picked a goat. So when you expose the other goat, switching would be the best idea since there are only three cards, one goat exposed, and the selected card is most likely to be a goat. If they still dont get it, say that the only way that switching WOULDNT work is if they originally chose the door with the car behind it. What did they say were the chances of that happening...?
It's up to you and your own creativity to decide when and how you present this, and definitely consider who you're talking to about it because you dont want to bore some dumb babe; it could be a big turnoff. But If you can do it well and make it seem interesting, it can be powerful. I've used it a few times and have always liked my results. normally i'll try to use a visual representation by putting three items on the table to represent the doors (Cellphone, wallet, and if she's smoking, my cigarette pack).
One notable experience I had with this (which gave me the idea of using this as a kind of story/convo) was when after I explained it, she understood it and I seriously was quite amazed. I asked her what she was majoring (college) in and told her that the reason I'm curious is because I've never seen anybody understand that problem so quickly after I explained it. That was when her eyes really sparkled and her smile grew even bigger. This is why it's important for me to be able to explain the problem well.
search youtube for "Monty Hall Problem" if my explanation wasn't quite up to par