Marcus Morris is opening up on his arrest and the allegations he stole hundreds of thousands of dollars from two Las Vegas casinos ... and he's adamant the whole ordeal is just one big misunderstanding.
The NBA player took to his Instagram page on Wednesday morning to share his side of the story for the first time since he was thrown behind bars in Florida on Sunday ... and in a lengthy post, he explained the drama all stemmed from when he recently took "out a marker to gamble" in Vegas.