If you have ever travelled internationally, you’re probably familiar with the customs card: a little piece of paper that you fill out without thinking, an irritating formality. But last summer, this tiresome task turned into a major pain in the neck. While returning from the Spanish class trip to Peru, Charlie Penn and Grayson Glass experienced a major hold up in border patrol, all because of one little check mark.

As usual, the group was required to fill out a border patrol form upon arriving back into the United States. Along with the yes or no questions about the value of gifts and types of food they were bringing back with them, the students and teachers were also asked if they had come in contact with any native animals in the country they visited. “I checked [the yes] box, assuming it was only the right thing to do,” Grayson says, as the students did go to a petting zoo during the trip, where they visited alpacas and llamas. However, they weren’t meant to check this box. “We didn’t get the memo,” Charlie explains, “so when we went through customs, they redirected me and Grayson.”

At first, they didn’t realize why they were separated from the group. But, “one thing that we had in common was that we both had checked this particular box on the customs sheet,” Grayson says. As an officer confiscated their passports, Charlie recalls thay, “[Profe Felty] figured out what happened pretty quickly,” and managed to intervene. The guys were taken behind a curtain and their shoes were sprayed with a disinfectant. “The funny thing is that my pair of shoes that he sprayed were not even the pair that I was wearing on the day that we went to the animal zoo,” says Grayson. This entire ordeal delayed the already-late group half and hour though. “We literally sprinted to make it to security,” Grayson remembers, “Without [Profe Felty and Profe Larson’s] help, I don’t know if we would have made the flight at all.”

There is one thing we can all learn from this experience: be careful of what you mark on your customs sheet!