Baby and Me (movie, 2008)

Joon-soo is a rebellious high school kid who often get in fights. One day, his parents give him an ultimatum and leaving him alone in the house, Joon-soo decides to have a party at his parent's home. He then goes shopping for groceries and comes upon an unexpected surprise. A little toddler sits in a shopping basket wearing the name tag "Han Woo-ram" and points to Joon-soo as his father.