When people talk about building a second income stream, the conversation usually revolves around stocks, mutual funds, startups or cryptocurrency. But sometimes the most profitable opportunities are surprisingly ordinary. A recent story shared by social media influencer Pratham Khanna has caught attention online for exactly that reason. It involves a software engineer in Gurgaon whose side hustle has nothing to do with technology, yet reportedly generates an additional Rs 15-20 lakh every year.Buying coconut water led to an unexpected discoveryPratham Khanna took to X to share an interesting conversation he had while stopping at a coconut water cart near his home. Curious about the business, he asked the person running the cart how many coconuts were sold on a typical day.According to Khanna, the worker responded that daily sales usually ranged between 300 and 400 coconuts. With each coconut priced at around Rs 80, that translates to roughly Rs 20,000 to Rs 25,000 in daily revenue from a single cart. At first glance, it seemed like the man behind the counter was operating a thriving small business.But that assumption turned out to be wrong. The cart owner wasn't the person selling the coconuts. Khanna said the worker laughed when asked about ownership. The man explained that the cart did not belong to him and that he was merely an employee managing daily sales.That revelation was only the beginning. The employee then shared a detail that surprised Khanna even more.According to him, the owner operates not one but four coconut water carts. Even more remarkably, the owner is not a full-time vendor.— Portfolio_Bull (@Portfolio_Bull) Gurgaon techie by day, entrepreneur on the sideThe employee revealed that the person behind the business works as a software engineer at a large company in Gurgaon. Despite having a corporate career, he has built an additional income stream through his coconut cart network. As described in Khanna's post, the routine is simple but disciplined.Every morning, the owner purchases and distributes stock across all four carts before heading to his office job. After finishing work, he returns in the evening to collect the day's earnings and oversee operations. The arrangement allows him to maintain a full-time career while also running a small offline business.How much does the side hustle generate?According to the details shared by Khanna, the software engineer earns a monthly salary of approximately Rs 1.5 lakh from his primary job. However, his coconut cart business reportedly generates an additional Rs 15-20 lakh annually. The figures immediately drew attention because they challenge common assumptions about wealth creation.Khanna summed up the story with a simple observation. Sometimes, he noted, "the richest side hustle is hiding in plain sight."Internet reactsInternet users had mixed reactions to the story. Some described coconut vending as one of the best cash-flow businesses and wondered about the tax implications of such an operation. Others argued that a well-run business can often outperform a traditional job, not only by generating wealth for the owner but also by creating long-term value for future generations. Several users also stressed the importance of looking beyond revenue figures, pointing out that costs such as purchasing inventory, transportation, employee salaries, initial investment and day-to-day operating expenses must be considered before estimating the actual profit.