Got the same thing. Tobi isn't my real name, but it's the name I use on most social media sites and I'm pretty much known online exclusively by that name. I got a message thinking maybe it was someone from YouTube or a friend from Facebook, but the number said to add them on Yahoo! Messenger under the name textgirly91, and while I attempted to re-install the program on my computer, I searched the name on Google, but found nothing. I was, luckily, unable to download the program, so I couldn't add them.
I noticed someone mentioned LinkedIn, but I don't have an account there. So they must be getting our information from other sources. The only places my number is listed are Facebook, but it's only available to people on my friends' list, and on YouTube, and even then, I only gave the number out in one of my videos, one that is not well-traffic'd, and most likely taken as a joke by many.
I'm just glad I was able to find you guys on here, and maybe we can figure out what the hell is going on.