“If each day us a gift, I would like to know where I can return Mondays” is a jocular one-liner that has been printed on many images. “If each day is a gift, I’d like to know where to return Mondays” was published in the newspaper comic strip “Crabby Road” on July 10, 2000, spoken by the “Maxine” character.
 
There have been several small wording variations, such as “each day” or “every day,” and “return Mondays” or “return Monday.”
     
 
10 July 2000, Sun-Sentinel (Fort Lauderdale, FL), “Crappy Road” (a “Maxine” comic strip), pg. 7D, col. 1:
If each day is a gift, I’d like to know where to return Mondays.
 
25 October 2000, PR Newswire (New York, NY), “Hallmark’s Outspoken Maxine Character Gets an Agent”:
KANSAS CITY, Mo., Oct. 25 /PRNewswire/—Hallmark Cards, Inc. has signed with International Creative Management, Inc. (ICM) to seek opportunities for Maxine, the popular greeting card character with an attitude. ICM will work to negotiate agreements in the fields of motion picture, television, radio, live stage productions and Internet entertainment.
 
Maxine, the opinionated, funny character created by Hallmark artist John Wagner, celebrates her 15th anniversary at Hallmark this year. Hallmark has sold more than 200 million Maxine cards since her launch in 1986, and the witty, flippant, irreverent lady of one- liners has become a reflection of American popular culture.
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—“If each day is a gift, I’d like to know where to return Mondays.”
 
Twitter
aaaalegna‏
@aaaalegna
“If each day is a gift, I’d like to know where to return Mondays.”
7:02 AM - 1 Dec 2008
 
Twitter
SuMeroValedor‏
@SuMeroValedor
...If every day is a gift, I want to know where to return Mondays !!!! -Maxine rules-
11:27 AM - 2 Mar 2009
 
Twitter
Gena Thomas‏
@hayleesnanny
If each day is a gift, I’d like to know where to return Monday’s.
12:11 PM - 10 Aug 2009
 
Twitter
ThePartyAnimal‏
@thepartyanimal
If each day is a gift, then where can I return Monday or at least exchange it for a Friday?
6:49 AM - 14 Sep 2009
 
Google Books
5,000 Great One Liners
Compiled by Grant Tucker
London: Biteback Publishing
2012
Pg. ?:
If every day is a gift, I’d like to know where I can return Mondays.
 
Google Books
Off The Top Of Fred’s Head
By Fred Lavner
Lulu Books (Luu.com)
2015
Pg. 215:
If each day is a gift I’d like to know where I can return Mondays.
 
Twitter
Lord & Taylor‏
@lordandtaylor
If every day is a gift then where can I return Monday?
2:55 PM - 3 Jan 2016
   
Quote Sigma
50 Best Monday quotes
Freeda Gillbert May 9, 2016
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15. If each day is a gift. I’d like to know where I can return Mondays