Mary Looper was over the moon about seeing Carrie Underwood perform at L.A's Staples Center last week—until security removed her from the women's restroom, thinking she was a man.

Looper and her aunt were attending singer's "The Storyteller Tour" when a guard stationed outside the stall she was using asked her to prove her gender.

"Usually I don’t want to put my drama out there but ignorant people still exist and it breaks my heart... They literally just tried to escort me out of the women’s restroom at the #staplescenter... Shame on them."

It's not the first time Looper has been mistaken for a man.

"But, the fact that their woman employee waited outside my stall for proof that I was a woman, didn’t believe me off my voice... That’s what hurt and had me shocked. I didn’t wanna stir anything up but never ever thought I’d be treated like that in a woman’s restroom in LA, in the Staples Center. Just a bummer it went that far."

We can only imagine what would have happened if Looper was a trans woman.

Staples Center’s Facebook page filled up with criticism about how the incident was handled.

"They harass women for using the women’s room, even if they are cisgender, if they aren’t feminine enough," wrote one person.

"There’s no excuse for this. The security guard in question did far more harm than that poor woman would have even if she was trans. [Staples] Center needs to fire this guard and make a public announcement that they will never stand for employees harassing people in bathrooms who are doing nothing wrong again."

Looper says she and her aunt still had a great time, though "the other stuff kinda put a damper on the night."

h/t: Raw Story