Dogs are highly intelligent creatures—and the smartest ones learn things by simply observing the world around them. A perfect example of this is a black dog named Negro who lives in a school in Colombia. He is a guardian, keeping an eye on students in their daily routine, which the school authorities have rewarded by providing him with food, water, lodging, and a lot of love. The students quickly developed a bond with the pooch and began getting him cookies sold at the small school store. Soon, Negro noticed a pattern—the pupils handed paper bills to the attendant and got a treat in exchange. Having deciphered the transaction—and wanting more cookies—the dog gave it a go. And so, the dog picked a leaf from the ground and approached the register, hoping to get a treat. “He would go to the store and watch the children give money and receive something in exchange,” teacher Angela Garcia Bernal from Colombia’s Diversified Technical Education Institute of Monterrey Casanare told The Dodo. “Then one day, spontaneous, he appeared with a leaf in his mouth, wagging his tail and letting it be known that he wanted a cookie.”

Of course, no one could say no to the pup, and he got his cookie. Having seen it work once, Negro came back over and over for his treat, always with his trusted form of payment. To keep him healthy, they only give him cookies safe for dogs and don’t give him more than a couple a day—despite how irresistible his face is. “He comes for cookies every day,” said Gladys Barreto, who has run the store for a long time. “He always pays with a leaf. It is his daily purchase.” Negro’s clever behavior has charmed everyone at the school, and his unique method of “paying” for cookies with a leaf showcases not only his intelligence but also the deep bond and understanding he shares with the students and staff. This delightful anecdote highlights the remarkable observational skills and adaptability of dogs, as well as the heartwarming ways they integrate into human communities.