"Love means nothing to a tennis fan/player” is a jocular saying that has been printed on many gift items, such as T-shirts, buttons and posters. The joke is a pun on the word “love,” meaning a “zero” score in tennis.
Forms of the joke have been told for at least 100 years. “In the tennis court, as in the divorce court, love means nothing” was cited in print in 1913. “Love means nothing to a tennis player” was cited in print in 1932.
Another tennis “love” joke is:
Q: What’s the definition of endless love?
A: Stevie Wonder and Ray Charles playing tennis.
10 June 1913, Idaho Statesman (Boise, ID), “Sassy Squibs,” pg. 4, col. 3:
In the tennis court, as in the divorce court, love means nothing.
17 June 1928, Greensboro (NC) Daily News, pg. 6D, col. 4:
“Many a girl finds a husband on the tennis courts,” declares a famous authoress. And yet that is the place where love means “nothing.”
25 May 1932, San Diego (CA) Union, “Flapper Filosophy” by Faith Burrows, pg. 2, col. 3:
Love means nothing to a tennis player.
1 June 1936, Seattle (WA) Daily Times, “Flossie” (comic strip) by Zere, pg. 23, col. 4:
“I’m through with tennis players. Love means nothing to them.”
OCLC WorldCat record
In tennis, love means nothing.
Author: Linda Jacobs Altman; Paul Snyder
Publisher: St. Paul, Minn., EMC Corp. 
Series: Her Winners all
Edition/Format: Book : Fiction : Juvenile audience : English
As an important tennis tournament creeps closer, Laura discovers that time spent with her boy friend can’t make up for time sacrificed from the practice courts on his behalf.
Google News Archive
14 September 1977, Miami (FL) News, pg. 1C, col. 1:
NEVER FALL IN LOVE WITH A TENNIS PLAYER, FOR LOVE MEANS NOTHING TO THEM: ...
Google News Archive
18 February 1978, Observer-Reporter (Washington, PA), “Box Seat” by Byron Smialek, pg. A-6, col. 2:
Thought for the day: Love means nothing to a tennis player.
Figure Skating Universe
06-29-2012, 08:34 PM
Never date a tennis player - love means nothing to them.