Completely useless extension turns laptop adapter into power strip

It's 2:30pm at your favorite cafe, and not a single power outlet's available to save your dying laptop from its fate. You're screwed, but a world away, your Japanese counterpart knows just what to do. They pull out this tiny little brick, stick it into the end of their laptop power supply, and deferentially ask another patron if they would kindly share. For the low, low price of ¥1,400 (about $15) for a two-prong version or ¥2,000 ($21) for three prongs, it's a fantastic idea... for mooching money off those who've never heard of a triple tap.