I've gotten Win32:Tenga-B and some stupid Virus when I click on Returntoblockland.com or a popup, Firefox 2.2 would say you are being redirected to Spycrush, Spysheriff, Antivirus 2009 (WTF 2009) and all those bad sites. Eventually AVG 8.0 bumped in and deleted the Virus.
Unfortunally for Win32:Tenga-B, it was very severe, my Computer would be dead if I had it on my Computer for too long, well I did not know how I got it, it infected Blockland, WOW, And nearly my whole Hard-drive.
Im thinking it was some kind of Trogan Downloader.
I got rid of it using Avast Virus Cleaner.