“Laughter is the closest/shortest distance between two people” has been credited to Danish comedian and pianist Victor Borge (1908-2000), who used several variations of this saying. “The shortest distance between two people is a smile,” Borge told an audience in 1969. “Laughter is the shortest distance between two people,” he told an audience in 1972. Borge’s saying has been frequently cited.
 
   
Wikipedia: Victor Borge
Børge Rosenbaum (/ˈbɔrɡə/ bor-gə; 3 January 1909 – 23 December 2000), known professionally as Victor Borge, was a Danish comedian, conductor and pianist who achieved great popularity in radio and television in the United States and Europe. His blend of music and comedy earned him the nickname “The Clown Prince of Denmark”, “The Unmelancholy Dane”, and “The Great Dane”.
 
2 March 1969, The News and Courier (Charleston, SC), “Victor Borge Keeps Audience Laughing” by Claire McPhail, pg. 4-A, col. 2:
As Borge said at the end of his program, “The shortest distance between two people is a smile.”
 
13 July 1972, The News and Courier (Charleston, SC), “Laughter cures ills” by Vivian Brown, pg. 10-C, col. 1:
GREENWICH, Conn. (AP)—Laughter is the shortest distance between two people, commented comedian and concert pianist Victor Borge. We should laugh more to enjoy our families and our work.
   
Google Books
Handbook of Humor Research:
Applied Studies
Edited by Paul E. McGhee and Jeffrey H. Goldstein
New York, NY: Springer-Verlag
1983
Pg. 8:
Coauthoring a humor book of this kind is a delightful way to operationalize Victor Borge’s notion that “laughter is the shortest distance between two people.”
   
Google Books
I’ll Walk Again
By Andy Reinert and Bink Burke
Chicago, IL: Burke Pub.
1986
Pg. 7:
Laughter is the closest distance between two people.
 
5 August 1986, The Daily Herald (Arlington Heights, IL), “Cryptoquote,” sec. 2, pg. 5, col. 2:
Yesterday’s Cryptoquote: LAUGHTER IS THE CLOSEST DISTANCE BETWEEN TWO PEOPLE. — VICTOR BORGE
   
Google Books
Humor
Mouton de Gruyter
Volume 1
1988
Pg. 389:
“Laughter is the closest distance between two people.”
Giacomo Leopardi
   
Googel Books
The Joyful Child:
A Sourcebook of Activities and Ideas for Releasing Children’s Natural Joy
By Peggy Davison Jenkins
Tucson, AZ: Harbinger House
1989
Pg. 185:
Let’s remember the words of Victor Borge: “Laughter is the closest distance between two people.”
   
Google Books
Humor
Mouton de Gruyter
Volume 10
1997
Pg. 112:
Humor is, in Victor Borge’s words, “the shortest distance between two people”.
 
Google Books
Wise Quotes of Wisdom:
A Lifetime Collection of Quotes, Sayings, Philosophies, Viewpoins and Thoughts
By R. A. Wise
Bloomington, IN: AuthorHouse
2011
Pg. 133:
Laughter is the closest distance between two people. –Victor Borge
 
Twitter
Brian Foley
‏@brianmichaelf
“The shortest distance between two people is a smile.” -Victor Borge
8:30 PM - 12 Nov 2015
 
Twitter
Jewish Comedians
‏@JewishComedians
Victor Borge: Laughter is the closest distance between two people. | #Quotes
5:53 AM - 14 Nov 2015