Crack undertones on "Keeping Up with the Kardashians" last night ... when Khloe took a bizarre phone call from a confused Lamar Odom ... and couldn't deny that something was clearly wrong.
During the scene, Lamar demands to know Khloe's location -- because he was told she was at another location doing something wrong.
But Khloe shoots back -- saying, "You keep calling me at my mom's [house] so you know where I am."
Khloe, clearly annoyed with Lamar, says he's not being "logical" -- and then starts making excuses for him ... saying he seems "tired."
At one point, Khloe tells Lamar ... "Listen, you're buggin' just a little bit."
It's unclear when the scene was shot -- but as we previously reported, Lamar's been struggling with crack for a while ... going out of his mind on multiple binges.