The USB condom is an adapter which disables the two data ports present on your USB connector to prevent a malicious charger from installing interesting things on your smartphone, if you decide to stick it into a strange charger.  Many will immediately point out that this device is much larger than a simple power adapter which makes it easier to leave behind as well as being large enough to hide nasties of its own, so you wouldn't want to borrow someones condom.  If you read through the comments on Slashdot you can pick up some interesting problems that this device could cause, from devices which refuse to charge without their data connections active to devices which actively communicate the amount of power they will accept for a charge.  It is unlikely your device would have an expected amperage less than the USB spec and go up in flames but it is worth knowing that the possibility exists.

"Yep, a USB condom. That term is mostly a dose of marketing brilliance, which is to say that grabs your attention while also serving as an apt description of the product. A little company called int3.cc has developed a product—a USB condom—that blocks the data pins in your USB device while leaving the power pins free. Thus, any time you need to plug a device such as a smartphones into a USB port to charge it—let's say at a public charging kiosk or a coworker's computer–you don't have to worry about compromising any data or contracting some nasty malware. It's one of those simple solutions that seems so obvious once someone came up with it."

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