It’s exactly what you think, a towel and a bikini so you don’t have to bring a towel with you. Of course, we can’t imagine the type of tan lines you’ll get with this. If you look closely, seems like your backside would be exposed if you stand-up. You may still need to wear something underneath. Weird.
More on the Towelkini here: Towelkini on Yahoo.
You can find some similar looking ones on eBay starting at $19.99 and other outlets if you google it. The authentic one will set you back $199. Find that one here: Towelkini.us. You’ll want to buy some kind of shorts while you’re at it.