Here's the deal ... Khloe posted an Instagram photo Friday showing her taking an outdoor shower in a skimpy bikini, and Lamar complimented her in the comments, telling her she's a "hottie" ... a response Tristan's not taking kindly.
Tristan tagged Lamar in the comments and then seemed to loft a threat his way, writing ... "@lamarodom God brought you back the first time. Play if you want, different results 🤷🏽♂️🤷🏽♂️"
The comment is obviously referring to Lamar's infamous 2015 drug overdose at a Nevada brothel, which nearly killed the former NBA stud.
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As you know ... Tristan's got a child with Khloe, but she's got a long history with Lamar. Khloe and Odom were married from 2009 to 2016 and they had their own reality show, "Khloe & Lamar."