這個拼法底下其實是2個不同的字，意思沒有關係， 只是長得一樣。下面分開列出來。跳到 平口上衣、管狀背心 · 電視（帶貶意的老俗語）
boob tube
noun核心畫面
Here the picture is simply a tube of cloth. A wide band, pulled on and left sitting around the chest, with nothing over the shoulders holding it up. Both halves of the name are doing plain descriptive work: what shape it is, and where it sits.
這一條的畫面就只是一圈布。一條有彈性的寬布，套上去以後停在胸口，肩膀上沒有任何東西幫忙撐住。名字的兩半各做一件很直白…更多收起
這一條的畫面就只是一圈布。一條有彈性的寬布，套上去以後停在胸口，肩膀上沒有任何東西幫忙撐住。名字的兩半各做一件很直白的事：一半講形狀（管子），一半講位置（胸部）。From the word’s history
The clothing sense is explained as a tube-like garment covering the breasts, first appearing around 1977.
衣服這個意思，來源說明是「一件管子形狀、圍住胸部的衣服」，大約在 1977 年第一次出現。
Wiktionary etymology supplied in packet (kaikki:3f6f69a190036ae4:812530273:6431): due to the clothing being a tube-like garment that covers the breasts; first use c. 1977 in the Daily Mail.
A second word, same spelling
boob tube
noun核心畫面
One way to hold this one: an old television set with a glass picture tube inside it, glowing in a dark room, and somebody sitting in front of it who has stopped thinking. The name is a joke made at both ends of that picture, at the box and at the viewer. Because the picture tube itself has gone, the expression now carries the smell of an earlier time.
可以想成一台老式電視機，裡面裝著玻璃映像管，在暗暗的房間裡亮著，前面坐著一個已經放空的人。這個名字同時在笑畫面的兩端…更多收起
可以想成一台老式電視機，裡面裝著玻璃映像管，在暗暗的房間裡亮著，前面坐著一個已經放空的人。這個名字同時在笑畫面的兩端：笑那台機器播的東西，也笑看的人。而因為映像管早就不用了，這個說法今天聽起來也就帶著上一個年代的味道。From the word’s history
The television sense is explained as boob (a fool, and the supposed audience) plus tube (the cathode ray picture tube in sets of that time), first appearing around 1959.
電視這個意思，來源說明是 boob（傻瓜，指節目和它假設的觀眾）加上 tube（當年電視機裡的映像管），大約在 1959 年第一次出現。
Wiktionary etymology supplied in packet (kaikki:3f6f69a190036ae4:812530273:6431): allusion to the idiocy of television programming and the supposed audience (boobs), and the cathode ray tube; first use c. 1959 in The Herald Journal.