Joo-bong is a father who raised his children alone while working as a real estate agent. His son, Seong-joo, has been preparing for the civil service exam for years but hasn’t made much academic progress. He relies on his father for allowance money, which he often spends on nightlife and on sending virtual gifts called Star Balloonsto an internet erotic BJ named ‘Bbung’, revealing his immaturity. Meanwhile, Joo-bong’s younger sister, Mi-joo, who lives with them, hides the truth from her family — she claims to run an online shopping mall, but in reality, she’s living a double life as an adult BJ. One day, while delivering laundry to Mi-joo, Seong-joo accidentally discovers that she is, in fact, BJ Bbung — leaving him completely shocked. Meanwhile, Mi-ja, a single mother, moves in next door to Joo-bong’s house along with her stepson, Sang-woo, with whom she is having a sexual affair despite their mother-son relationship. From that point on, the two families become entangled in an absurd and risqué series of sexual mishaps.