Andrea Ownbey -- aka the reigning 'Miss Howard Stern' pageant winner -- was arrested for DUI earlier this month ... after cops say she drunkenly smashed into another car and didn't even realize it.
According to the police report, obtained by TMZ ... 29-year-old Ownbey -- who's been Miss Howard Stern since 2002 -- hit another car on the streets of Chattanooga, Tennessee sometime after 10pm on October 8.
A cop who happened to be in the area, claims he heard the accident and rushed to the scene -- only to find Ownbey in her car ... reeking of booze ... and fumbling to put her cell phone back together.
In the report, the cop states, "[Ownbey] was not aware that she had been in a traffic crash."
The officer claims Ownbey admitted to drinking two glasses of wine before getting behind the wheel ... so he administered a field sobriety test ... and she bombed.
And to make matters worse, cops say they found a small baggie of weed in the car ... as well as a weed pipe and a variety of prescription drugs.
According to the police report, Ownbey was transported to a nearby hospital -- where she took a breathalyzer test ... and blew a .178 ... way over the legal limit, .08.
Once she was medically cleared, Ownbey was taken to a nearby jail where she was booked for DUI, possession of drug paraphernalia, possession of a controlled substance and driving while in possession.
We also spoke with the driver of the car Ownbey hit who tells us Andrea came "flying out of nowhere" and rear-ended him HARD. The driver says his Jeep was totaled in the wreck.
We reached out to Ownbey -- so far, no response.