The “boob tube” is a nickname for the television—a tube (cathode-ray tube) for boobs (idiots).
 
“As a chronicler of the boob-tube, I have received hundreds of letters, but the bulk of them fall into predictable categories and can be answered rather simply” was written by William Ewald, a UPI television writer, and printed in many newspapers on August 14, 1999. William Ewald, who was also an assistant managing editor of the Daily News (New York, NY), died in 2008 at age 82.
 
   
Wiktionary: boob tube
Etymology
. (television): An allusion to the idiocy of television programming and the supposed audience for such (boobs) and that televisions of the era used cathode ray tube (CRT) vacuum tube displays
. (clothing): From it being a tube-like garment that covers the breasts (boobs) of a woman
Noun
boob tube (plural boob tubes)
1. (US, informal, dated, derogatory) television
Synonym: idiot box
2. (Britain, informal) A type of woman’s upper body garment consisting of a taut band of cloth around the breasts and back.
Synonym: tube top (US)
 
(Oxford English Dictionary)
boob tube, n.
colloquial (originally and chiefly North American).
Television; a television set. Cf. tube n. 2k.
Chiefly with disparaging implication.
1959   Herald Jrnl. (Logan, Utah) 14 Aug. 3/1   As a chronicler of the boob-tube, I have received hundreds of letters.
1966   Current Slang (Univ. S. Dakota) Fall 1   Let’s catch the late show on the boob tube.
 
Newspapers.com
14 August 1959, The Herald-News (Passaic-Clifton, NJ), pg. 21, col. 3:
Ewald Calls It Quits
Chronicler of the Boob-Tube Sings Swan Song Without Remorse for What He’s Said
By William Ewald
NEW YORK (UPI)—Dear Reader: This is my last gasp as a TV columnist.
(....) (Col. 4—ed.)
As a chronicler of the boob-tube, I have received hundreds of letters, but the bulk of them fall into predictable categories and can be answered rather simply.
 
Newspapers.com
18 November 1959, Idaho State Journal (Pocatello, ID), pg. 8, col. 1:
Don’t Be Tube Boob
Where Else Could You Learn How to Shave Sandpaper?
By CYNTHIA LOWRY
AP TV-Radio-Writer
NEW YORK (AP)—Some people complain, but there are those among us who find television commercials highly education.
 
OCLC WorldCat record
The ‘Boob Tube’ Goes to High School
Author: William H Rigby; Ronald H Fricker
Edition/Format: Article Article : No language available
Publication: Ind Arts Vocat Educ, 58, 6, 34-35, 69 June
 
OCLC WorldCat record
Television: A “Good Tube or a “Boob” Tube?
Author: James A DeShazer; Donald M Edwards
Edition/Format: Article Article : No language available
Publication: Engineering Education, 63, 6, 417-420, Mar 73
Summary:
Discusses the advantages and disadvantages of using in classroom two types of television instruction: videotape recordings and live programs. (CC)
 
OCLC WorldCat record
The official TV trivia quiz book ; #2 : 1,001 boob-tube teasers for media maniacs
Author: Bart Andrews
Publisher: New York : New American Library, 1976.
Series: A Signet book
Edition/Format:   Print book : English
 
OCLC WorldCat record
Television Programming: The “Boob Tube” Takes a Bum Rap
Author: John E Jr Baird
Edition/Format: Article Article : No language available
Publication: Intellect, 104, 2375, 590-93, May/Jun 76
Summary:
Attempts to test objectively one of the most prominent criticisms—that television programming is imitative and restrictive of viewer choice—in an effort to determine whether that criticism is legitimate. (Author/RK)
 
Urban Dictionary
boob tube
A slang term for television.
“Parents complain about the quality of the shows but don’t prevent their children from gluing themselves to the boob tube” (David Owen)
by illEATurHARTout April 13, 2004
 
Newspapers.com
19 January 2008, Daily News (New York, NY), “Obituary: Ex-News editor Edwald, 82” by Owen Mortiz, pg. 21, col. 1:
William Ewald, a former assistant managing editor of the Daily News and an influential figure in magazines and publishing, died Dec. 26 of leukemia in La Jolla, Calif., his family said yesterday. he was 82.