Lil Nas X Strips Down Nude Before Arrest, See Video

You might want to hold onto your undies for this one -- Lil Nas X was spotted completely naked before his arrest this week ... and we've got video of the stunning moment.

Check out our clip -- he's strolling down the street while singing after ditching his underwear and boots somewhere in Los Angeles. He seems completely unfazed by his lack of cover ... even making eye contact with the camera as he puts on a show.

And if you didn't notice ... he's belting some Nicki Minaj lyrics, specifically her line in "Monster" by Kanye West.

We're told he was spotted running free around 5:45 AM Thursday, not long before police picked him up and had him transported to a hospital for a possible overdose.

TMZ learned bystanders had reported to LAPD that they saw a nude man walking down the road prior to his arrest ... and now, we see their reports were accurate.

We also obtained footage of the "Old Town Road" hitmaker before he lost his undies ... strutting down Ventura Blvd at 4 AM in his underwear and matching cowboy boots, warning the folks behind the camera not to miss the party.

At one point, he confidently belted out some bars ... and then placed a traffic cone on his head during another part of the bizarre clip.

Lil Nas was eventually transported from the hospital to a jail cell on Thursday ... and we broke the news Friday that Lil Nas must stay behind bars until Monday.

We're told he was arrested on suspicion of battery on a police officer ... so he needs to face a judge to have his bail set -- which won't be until at least Monday.