Of the roughly 5.5 million vending machines in Japan (the highest density of such machines on the planet), the beverage component (including beer) generated a staggering $27 billion last year. The remaining machines dole out things like candy, food, cigarettes, tickets, and toys. But if you follow the sensational random reports from various blogs, you'd think the streets were lined with machines spitting out lady's undergarments, and various other perverse curios of Japanese arcana.
The truth is that although there are indeed vending machines that dispense such underground items, these machines are almost exclusively limited to specialized establishments that cater to, well, unique customers. You could spend a year traveling throughout Japan and never see anything more threatening in the public machines than a fattening chocolate snack.
Read more about Japan's robots, Internet Cafes, school girls (yes, it's an article about Japan so school girls are required), and Electric City at Dvice.