Re:In Britain, A Boob Tube is... (Score 2, Informative)

In North America, Boob is sometimes used as a replacement for idiot or fool (What a boob!). Tube is sometimes used as a replacement for TV or Telly (What's on the tube?). Boob Tube is synonymous with Idiot Box, which refers to the idea that watching television inherently makes you stupid because of all the crap on TV.

The Boob Tube that you refer to is usually referred to as a Tube Top here in North America. Maybe we don't call them Boob Tube's here because they are becoming quite popular (much to the dismay of their parents) with pre-teen girls who haven't developed boobs yet ;-)