The woman accusing Auston Matthews of dropping his pants in front of her was LIVID over the whole situation ... saying of the NHL star, "What the f**k were you thinking?!"
It's all in new police video obtained by TMZ Sports ... in which the female security guard tells an officer all about a May 26 incident where she says Matthews and his friends played a VERY unfunny joke on her.
She claims she was working a night shift at Matthews' residence in Scottsdale, AZ, when the hockey player and 2 of his friends tried to open her locked car door at around 2 AM.
As a military veteran ... she says she was legitimately frightened by the actions -- and then outraged when 22-year-old Matthews and his friends told her it was all just a joke.
"The minute you try to invade my space, what the f**k were you thinking saying, 'We wanted to see how you'd react if we got into the back of your car'?" the woman says.
"Are you serious right now?!? And then, they thought, 'Oh, you're a veteran so you're packing?' None of this s**t is funny!"
The woman also told the officer all about the scene where Matthews pulled down his pants ... saying one of Auston's friends tried to make her laugh over the whole thing.
"He turns around and he's like, 'You see that s**t he's doing? He's been doing that up and down Scottsdale Road. I keep telling him that he can get arrested by cops. And, he's like he doesn't give a s**t.'"
The woman adds, "And, he's laughing because he thinks I would laugh at the fact that his pants are down."
The woman also says Matthews' father tried to accuse her of lying about the whole situation when the condo's manager brought it up with him ... but said they were able to show him video of it all.
Eventually, the woman tells the cop she wants to press charges against Matthews.
In more police footage obtained by TMZ Sports ... you can see an officer try to interview the Maple Leafs star at his condo -- but he doesn't respond to the knocks.
Matthews is now fighting a disorderly conduct charge in Scottsdale ... and he said of the whole incident to reporters on Wednesday, "I regret any of my actions that would ever put a distraction on the team or distress any individual."
He added, "I take a lot of pride in preparing myself for the season and representing the Toronto Maple Leafs as well as I can. Unfortunately, due to the situation, I’m afraid I can’t really make any other comments."
Auston is due back in court next month to face the charge.