08/16/2012 10:08 pm ET Updated Aug 17, 2012

Sydney And Rylee Youngberg, South Dakota Girls, Use Lemonade Stand To Raise Money For Dad's Cancer (VIDEO)

Talk about a chore that paid off.

When Jennifer Youngberg's two daughters, Sydney and Rylee, decided to skip the pool and instead head for a non-lifeguard-protected dip in a river last month, she got angry.

And then she grounded them for the first time ever, she says, and informed them their only path to freedom was to do something nice or help someone in need, writes the Capital Journal.

The girls opted to start a lemonade stand, reports Keloland TV, typically a harmless activity. But when people started walking up, handing off large bills, then walking away, "I thought 'My gosh, what is going on outside?'" Jennifer said.

Then she noticed the sign, which read "All proceeds go to our dad who is fighting cancer, and winning!"

According to the Associated Press, Jennifer's husband, Mike, is fighting cancer for the second time. While she initially considered asking the girls to remove the sign, she says she didn't want to teach them not to perform kind acts.

At the end of the day, Sydney and Rylee's lemonade stand had raised an astonishing $6,000. We're guessing that's more than enough to get them out of trouble.

As for Mike's cancer, they received good news on that front, too. "His prognosis is excellent," said Jen.

H/T: Reddit