In 1933, Jack Crawford won the Australian, French, and Wimbledon Championships, leaving him just needing to win the last major event of the year, the U.S. Championships, to become the reigning champion of all four major tournaments,[17] a feat described as "a grand slam" by sports columnist Alan J. Gould of The Reading Eagle,[18] and later that year by John Kieran of The New York Times, who stated that if Crawford won at Forest Hills it "would be something like scoring a grand slam on the courts, doubled and vulnerable."[19][20] The term 'Grand Slam' originates from the card game contract bridge, where it is used for winning all possible tricks. In golf it was used for the first time to describe a total of four wins, specifically Bobby Jones' achievement of winning the four major golf tournaments of the era, which he accomplished in 1930.[20] "Grand Slam" or "Slam" has since also become used to refer to the tournaments individually.[4] The first player to win all four majors in a calendar year and thus complete a Grand Slam was Don Budge in 1938.[21]

(http://www.autoadmit.com/thread.php?thread_id=5711593&forum_id=2E#48853092)

your only issue is that each one can never be referred to as a slam.

(http://www.autoadmit.com/thread.php?thread_id=5711593&forum_id=2E#48853109)

comparing golf and tennis slams here is very apt.

(http://www.autoadmit.com/thread.php?thread_id=5711593&forum_id=2E#48855328)