Staff at a Notre Dame campus bar in South Bend, Ind. got a pretty spectacular surprise last month when a group of three generous men left two tips totaling $10,000, despite the fact that they seemed to be rooting for the opposing team. But because it’s not every day that such a sum lands in your lap, the staff is still waiting to get that cash due to fraud concerns.

“Fight on,” the cardholder wrote on his receipt on Oct. 19 after he paid the tab for his fellow University of Southern California fans who had been watching their team play Notre Dame. Then he added a $5,000 tip on their $84.06 bill, reports the South Bend Tribune.

“We were all looking at this like, is this a joke?” said a former bartender at the bar.

But the generosity wasn’t done yet — when the game was over the men came back and spent another $164.50 — and left another $5,000 tip.

Because he used his American Express card both times, the company and Notre Dame haven’t cleared the tips yet. There’s a worry about fraud, which means the three servers have yet to split the money.

“We’ve been working with American Express to determine the validity of the tip, and we hope and expect that question will be resolved soon,” a Notre Dame spokesman said, adding the university was in touch with American Express because of the “suspicious nature of the transaction.”

An American Express spokeswoman also doesn’t know when or if the servers will get their moolah, as the company can’t say when it’ll decide if the tips are legitimate.

As for the identity of this tipper or tippers, it’s unclear if it’s connected to someone using an Instagram account chronicling similar instances of largess around the country.

“They were trying to keep it confidential,” the former bartender says of the whole incident. “We had no reason to think it wasn’t real.”

Mystery tipper leaves $10,000 at bar [South Bend Tribune]

Want more consumer news? Visit our parent organization, Consumer Reports, for the latest on scams, recalls, and other consumer issues.