Something that is “like watching paint dry” is something that is very boring. “Waiting for them to score one (the Dodgers to score a run—ed.) is like watching paint dry” was cited in July 1967. “The guy who said, ‘Seeing the White Sox is about as exciting as watching paint dry,’ didn’t know what he was talking about” was cited in August 1967. The expression possibly originated with watching a particular team play baseball.
 
“Watch grass grow” is a similar expression.
 
   
Wiktionary: watch paint dry
Verb
watch paint dry (third-person singular simple present watches paint dry, present participle watching paint dry, simple past and past participle watched paint dry)
1. (humorous) To watch something that has virtually no movement, hence, something very boring.
 
(Oxford English Dictionary)
watching paint dry: in similative phrases, as the type of an extremely dull activity.
1969   B. Knight in N.Y. Times 11 Mar. 53/3   We’re excellent on defense, but as to our offense and scoring—well, there are three things they bring to mind. You can have your choice of watching a grease job, watching paint dry or watching our offense.
1972   R. W. Davis in Internat. Jrnl. Afr. Hist. Stud. 5 323   The book contains all the excitement of watching paint dry and reads like the history of a small teachers’ college.
       
19 May 1959, Los Angeles (CA) Times, Los Angeles (CA) Times, “‘The Shrike’ Offered at Horseshoe,” pt. 1, pg. 28, col. 4:
Sitting in attendance at the Horseshoe Stage Theater presentation of Joseph Kramm’s “The Shrike” is as exciting as watching paint dry.
 
14 July 1967, San Diego (CA) Union, “Cubs Halt L.A. Rally, Win, 2-1” by Phil Collier, pg. C-1, col. 6:
What the Dodgers tried to do was build a team that would score runs. Waiting for them to score one is like watching paint dry.
 
28 August 1967, Cedar Rapids (IA) Gazette, “Red Peppers” by Gus Schrader, pg. 15, col. 6:
CHICAGO — The guy who said, “Seeing the White Sox is about as exciting as watching paint dry,” didn’t know what he was talking about.
 
Old Fulton NY Post Cards
28 September 1967, Schenectady (NY) Gazette, “Sports Smorgasbord” by Marv Cermak, pg. 48, col. 1:
Talking about baseball, read where one sportscaster describes the White Sox as “about as exciting as watching paint dry.”
 
11 December 1967, State-Times (Baton Rouge, LA), “Lighter Side of the News” by Dick West (UPI), pg. 9-A, col. 1:
People who have never seen a congressional adjournment rush may winder what it is like. Well, probably the best description comes from Rep. Thomas M. Rees, D-Calif., who says it is like watching paint dry.
 
Google Books
How the Doctors Diet
By Peter Wyden and Barbara Wyden
New York, NY: Trident Press
1968    
Pg. 167:
She knows she should do the exercises more often, but as she put it: “It’s a bore — as boring as watching paint dry.”
 
Google Books
An Executive’s Primer on Public Relations
By John F. Budd
New York, NY: Chilton Book
1969  
Pg. VII:
A word, too, about my colleagues, a creative band of individualists who consider a public relations text as stimulating as watching paint dry, and as informative as a three-year-old release
 
Google Books
Patterned Fast-Break Basketball
By J. Ted Carter
West Nyack, NY: Parker Publishing Company
1971
Pg. 21:
As one coach put it, “It’s about as interesting as watching paint dry.”
 
OCLC WorldCat record
Worse than watching paint dry - Pentium PC chipset integrates synchronous SRAM cache . USD 149 buys 56002 evaluation module . ARM RISC targets communications, portable systems . Speeding up DSP development . Use BASIC to program C40-based data-acquisition boards
Author: Ray Weiss
Publisher: [Boston, Mass. : Computer Design Pub. Corp.,
Edition/Format: Article Article : English
Publication: Computer design. 34, no. 8, (1995): 107
Database: ArticleFirst
 
Urban Dictionary
Watching Paint Dry
Internet slang for staring at your download progress bar or watching download speeds fluctuate.
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by LashedOut2k March 26, 2009