Courtesy: Kennidi Rue

A trio of customers at a Taco Bell in Michigan drove to the restaurant's drive-through window Saturday expecting to receive the chicken burritos, two soft-shell tacos with no cheese and drink they'd ordered just moments before.

Instead, they received a bag containing their sales receipt, the sauces they ordered and $3,600 in cash.

"I was about to hand my boyfriend his food and I said, 'You guys, there's no food in here. It's just money,'" Kennidi Rue, 18, of Holland, Mich., told ABCNews.com. "I thought it was a candid camera joke."

There was no camera in sight for Rue, her boyfriend, Grant Kruse, 20, and their friend, Luke Postma, 25. The three were about a mile away from the Kentwood, Mich., restaurant when they discovered the cash jackpot and had a decision to make.

"We just sat there and said, 'What are we supposed to do?'" said Rue. "At first, we were like, 'Think about what we can do with this money,' but we weren't raised like that."

"We realized we should give it back," she said.

Postma - like Kruse, a National Guardsman who just returned in March from a 10-month deployment to Afghanistan - called the local police department to report the money and an officer escorted them back to Taco Bell.

When the good Samaritan trio handed the money to the restaurant's manager, she was overcome with emotion, according to Rue.

"The manager started bawling and was really shaken up and said, 'Thank you so much,'" she said. "Right there, we thought, 'Wow, we're so glad we did the right thing. It was obviously a big deal for her."

It was such a big deal for the manager, who was not identified, that she took the money to the back office and did not return to thank the trio again. Instead, Rue, Kruse and Postma just waited again to have their original, cash-less order filled.

"They fixed our order and gave it to us, and that was that," Rue said.

Taco Bell did not reply to a request for comment placed by ABCNews.com.

Rue said she and her friends were told that it is store policy to put cash register money into the to-go bags and, in this instance, the bag was simply misplaced.

Rue and her friends feel good about what they did, especially considering they'll likely never have the chance to do it again.

"I don't think that will ever happen to us ever again," she said. "[It was] the craziest thing ever, for sure."