“What’s the definition of endless love?”/“Two blind people playing tennis.”

“Love means nothing to a tennis player” is an old joke on the scoring in tennis (where “love” does mean nothing). Another joke is:
 
Q: What’s the definition of endless love?
A: Stevie Wonder and Ray Charles playing tennis.
 
The joke has been cited in print since at least 1983. A popular song at that time was “Endless Love” (1981), a duet with Lionel Richie and Diana Ross.
 
     
Google Books
National Lampoon
Volume 2, Issues 54-65
1983
Pg. 18:
Q: What’s the definition of endless love?
A: Stevie Wonder and Ray Charles playing tennis.
This joke originated backstage during a recent Grammy Awards presentation as Mr. Wonder was making an acceptance speech.
 
Google Groups: net.jokes
Definition of “Endless Love”
HP Labs Guest/guest
8/22/84
Stevie Wonder playing tennis with Ray Charles!!
 
Google Books
And I Quote:
The Definitive Collection of Quotes, Sayings and Jokes for the Contemporary Speechmaker (Revised Edition)
By Ashton Applewhite, William R. Evans III and Andrew Frothingham
New York, NY: Thomas Dunne
2003
Pg. 370:
Q: Know the definition of “endless love”?
A: Stevie Wonder playing tennis with Ray Charles.
 
Urban Dictionary
endless love
stevie wonder and ray charles playing tennis
by slims September 02, 2003
 
reddit
What do you call it when Stevie Wonder and Ray Charles play tennis? (self.Jokes)
submitted September 8, 2015 by [deleted]
Endless Love
 
Twitter
Clean Jokes
‏@CleanJokes247
#CleanJokes Q: What is the definition of endless love? A: Stevie Wonder & Ray Charles playing tennis! http://ow.ly/39DqZm
2:30 AM - 2 Jan 2016