“You can’t have your Kate and Edith, too” is a pun on the the famous saying, “You can’t have your cake and eat it, too. This was printed in the Chicago (IL) Daily Tribune on April 26, 1949:
 
“I first met a girl named Kate
And then Edith with eyes of blue,
But I couldn’t, I discovered,
Have my Kate and Edith, too.
—Joseph Charles Salak.”
 
“You Can’t Have You Cake And Eat It Too” was the title of a 1967 song by The Statler Brothers.
 
     
Wikipedia: You can’t have your cake and eat it
You can’t have your cake and eat it (too) is a popular English idiomatic proverb or figure of speech. The proverb literally means “you cannot simultaneously retain your cake and eat it”. Once the cake is eaten, it is gone. It can be used to say that one cannot have two incompatible things, or that one should not try to have more than is reasonable. The proverb’s meaning is similar to the phrases “you can’t have it both ways” and “you can’t have the best of both worlds”.
 
26 April 1949, Chicago (IL) Daily Tribune, “In the Wake of the News” by Arch Ward, pt. 3, pg. 1, col. 2:
Lithping Troubador
I first met a girl named Kate
And then Edith with eyes of blue,
But I couldn’t, I discovered,
Have my Kate and Edith, too.
—Joseph Charles Salak.
 
4 June 1952, Newsday (Long Island, NY), “It Happened Last Night” by Earl Wilson, pg. 82, col. 2:
Taffy Tuttle told one of the Broadway wolves: “You can’t have your Kate and Edith, too.”
     
13 March 1955, Atlanta (GA) Journal and Constitution, “Around Town” by Hugh Park, pg. 14-B, col. 1:
TIME TO DUCK: A story infiltrating TV studios here concerns a fellow who was dating two gals, keeping each ignorant of the other. There names are Kate and Edith. One day they met. It just goes to prove again that you can’t have your Kate and Edith, too.
 
7 April 1955, Courier-Post (Camden, NJ), “Walter Winchell On Broadway,” pg. 15, col. 3:
DID YOU HEAR the silly about the fellow in love with two gals? One named Kate, the other Edith. He couldn’t make up his mind.
 
“You’d better, warned a pal, “you can’t have your Kate and Edith too.”
     
6 May 1960, Daily News (New York, NY), “Sip and Sup” by Frank Ross, pg. 62, col. 3:
An actor was bemoaning that his wife and girl friend had found out about each other. “After all,” another guy said, “You can’t have your Kate and Edith, too.”
 
8 October 1978, Sunday Advocate (Baton Rouge, LA), “My Favorite Jokes” by Harvey C. Gordon, Parade magazine, pg. 31, col. 1:
A man was married to a woman named Edith and having an affair with a girl named Kate. His wife found out about the affair and divorced him, which goes to show that you can’t have your Kate and Edith too.
   
twitter
stevehickey
@stevehickey
Bad sermon title #52 On adultery- “You can’t have your Kate and Edith too”. #53 On the tongue: “Beware the Pink Tornado”
3:59 PM · May 29, 2009·Cloudhopper
   
Twitter
Timothy Bowman
@tbowman18
@ItWasMattGregg @jdgstewart “You Can’t Have Your Kate and Edith Too: A Lesson in Adultery” #worstsermontitles
11:29 PM · Jan 21, 2015·Twitter for Android
 
YouTube
The Statler Brothers ~ You Can’t Have Your Kate And Edith, Too
Wayne Harvey
Published on May 3, 2015
The Statler Brothers ~ You Can’t Have Your Kate And Edith, Too
     
Reddit—Jokes
Posted by u/exodus2327 July 26, 2015
So I met this girl at a party. Kate.
She’s really awesome and about as gorgeous as they come. Anyway, we went out a couple times and really hit it off and I eventually asked her to be my girlfriend about a month later… Then just a couple weeks ago this other girl, Edith, started working at the hospital in the same department as me and had been showing quite a bit of interest. She’s just as awesome and attractive as Kate but she has a little more of a bad girl streak in her (which is my kryptonite) so I couldn’t make up my mind of who I wanted. So I decided to go out with Edith to see it out and not tell Kate that I was going to do this. Eventually Kate found out about Edith and stopped talking to me completely..which is understandable. But then Edith got mad that I was seeing her while I already had a girlfriend and now SHE’S not talking to me. So now I have no one….I guess the moral of the story is: You can’t have your Kate and Edith too..
 
Reddit—Jokes
Posted by u/[deleted] April 8, 2017
I once loved two girls at a time, Kate and Edith
both were mine. I learned what they say is true….... You can’t have Kate and Edith too
 
Reddit—Jokes
Posted by u/SeymourAzzes June 11, 2017
John was unable to choose between two girls…
So he asked his friend Gary for help deciding which girl to be with.
John: I’m devoted to Kate but Edith is my dream girl, she’s all I’ve ever wanted.
Gary: Then you should be with Edith.
John: But I love Kate and could never leave her…
Gary: Then you should stay with Kate.
John: But I also want to be with Edith, I can’t miss this opportunity!
Gary: You can’t have your Kate and Edith too.
     
Twitter
~Marietta
@MariettaDaviz
Saw This On a Methodist Church Sign Today: 😇
ADULTERY IS A SIN.
YOU CAN’T HAVE YOUR KATE AND EDITH TOO.
8:31 PM · Sep 9, 2018·Twitter for Android
 
Reddit—Dadjokes
Posted by u/USAneedsAJohnson August 6, 2019
I dated two girls at the same time in high school.
Kate and Edith. They both found out pretty quick… taught me a good lesson… You can’t have your Kate and Edith too.