Many of Reba McEntire's fans already know that philanthropy is important to the singer: Over the years, she's lent her support to organizations including the Salvation Army, Habitat for Humanity, the Texoma Medical Center and more, plus her Reba's Ranch House in Texas helps people have a place to stay while supporting their hospitalized loved ones.

She's also a frequent supporter of Celebrity Fight Night, an annual charity event that draws stars from all corners of show business to raise money for cancer research. At an Arizona Fight Night event in mid-March, McEntire was part of the evening's entertainment, and she also auctioned off a chance for one fan to have dinner with her in Nashville.

But that evening, McEntire wound up giving a little more to charity than she bargained for, the singer recounted to Taste of Country and other outlets during a recent press event.

"I was the emcee, and I was wearing this beautiful gown that Johnathan Kayne made for me," she says. "It was beautiful, and had big bell sleeves. So I auctioned off a dinner to whoever wanted to go have dinner with me, and after that, I said, 'Does anybody want this dress?' Of course, the women kinda perked up, and they said, 'Yeah.'"

So McEntire made the impromptu decision to auction off her dress.

"We auctioned it off for $150,000," she continues, adding that the woman who bought it said that not only did she want it — she wanted to walk out of the event with it.

"I had to go change clothes. I had to get my jeans on," McEntire recounts. "Because...the woman who bought it, I know her, and she said, 'No, I want it tonight. I don't want you to take it home and dry clean it — I want you to give it to me now.'

"I said, 'Okay.' And I went and got my jeans and boots on," the singer adds. It was all in the name of a good cause, after all — the money went to funding cancer research.

Of course, McEntire has rocked plenty of iconic red carpet looks over the years, and she says she's still got a cache of some of her all-time best looks in a climate-controlled storage unit where they'll be safe — that is, until the next time she decides to pull one out for a surprise auction.

10 Surprising Things You Never Knew About Reba McEntire: