Jared Rosenthal, owner and operator of the "Who's Your Daddy?" truck, says the people of New York keep him busy all day every day.
"They flag us down, they pull us over, they talk to us," Rosenthal tells CBS New York. "Sometimes, because of the nature of the services, they want to be a little more discreet about it, but they do come or they'll call the number."
For as little as $300, Rosenthal takes a swab of a customer's inner cheek and results are available in a couple of days. He says some men have shown up with a baby for testing only to find out it's not theirs. But there have been positive results as well, like a man who found his long-lost daughter.
Because of the sometimes emotionally tense situations, Rosenthal says half the job is being a psychologist to his customers.
So, what's next in truck-based-businesses? Mobile beer canneries? Done. Blood donations? Done. Lasik surgery in a van? Coming soon!
Watch the video below for more of the story.