Generally, 'sport' is used simply as a friendly greeting.
It seems to be an old and easily translated expression.
In various translations of the Odyssey, Odysseus challenges the Phaetians in these words:
"He spoke to the Phaeacians now with a lighter heart.
‘Match that, you youngsters: ...' "
(Tr. A.S. Kline)
"... he spake amid the Phaeacians: 'Now reach ye this throw, young men, if ye may; and soon, methinks, ... "
(Tr. S.H. Butcher and A. Lang)
"... he said to the Phaeacians: Now then, young sports, match this throw, ..."
(Tr. Stephen G. Miller)