Khloe Kardashian's one and only Coachella experience "wasn't the best" ... because she was high as a kite after she says she accidentally took drugs at a party.

She said on Wednesday's episode of her "Khloe in Wonder Land" podcast that it's been a while since this went down -- she went to the music festival with Kylie and Kendall Jenner back in 2015 -- but it wasn't anything nefarious.

Khloe thinks there was a little something in the "juice" at the party she was at ... and everyone knew except her.

She said ... "I don't think anyone, like, drugged me. I just think I was the dumb one and didn't realize that everyone was on drugs."

Khloe said that she felt "really crazy" after having a drink ... to the point that she locked herself in the bathroom for hours and everyone was yelling at her to get out.

The reality star said she was freaked because she didn't know why she felt off, explaining ... "No one wants to feel like that and not know why."

Sounds terrifying ... seems like Coachella might be a one-and-done thing for Khloe after that.