Why did/do people refer to TV as "boob tube"?

I've heard this phrase so many times in my life I dont even think about it, but the more I dwell on it, I dont really get it

5 comments

"Boob" was/is slang for "stupid person," so the implication was that watching too much TV would make you stupid
- Oh that makes sense! Where does the tube come from though?
  
  Cathode Ray Tubes. Its how TVs used to work