Ex-NBA player Jordan Hamilton straight-up SPIT on an opponent during an Israeli Premier League game earlier this week ... and it's all on video.
It went down Wednesday when Jordan's Hapoel Holon squad took on Hapoel Eilat.
It's unclear why ... but Hamilton -- the Dallas Mavericks' first-round pick in 2011 -- hocks a nasty-ass loogie and sprays it all over the back of Amit Simhon's head.
Simhon tries to tell the refs on Jordan ... but he's only given a tech -- no ejection!!
THIS IS FLAT OUT GROSS AND UNPROFESSIONAL.