Ankit Mittal, of Ellicott City, Md., tosses a bean bag as his friend Shean Flynn, of Newport News, Va., waves his Terrible Towel as the two were playing Corn Hole while enjoying tailgating before the game between the Pittsburgh Steelers and Washington Redskins at FedEx Field in Landover, Md.

Every day after he leaves his job as a warehouse general manager, Cody Henderson runs up to three miles. Then, he sets up cornhole boards and practices throwing beanbags for a couple hours, focusing on timing, balance and precision.

"It helps a lot with the endurance and mental game," Henderson, 27, told CNBC. "If you can sit there and not get bored in a quiet area for two or three hours, you are really going to set yourself up to succeed on the pro level."

Succeed he has. Henderson, who lives in Jackson, Ohio, is the top-ranked player out of the 20,000 pros in the American Cornhole League (ACL). He says he earned between $20,000 and $25,000 in prize money last year. He's peaking just as the sport is surging in popularity.

While cornhole is generally thought of as a beanbag tossing game played at family gatherings or tailgate parties, it's gotten so big that players like Henderson are making their way to ESPN. During last year's The Ocho, a one-day event for alternative sports on ESPN 2, the Championship of Bags was the most viewed competition.

In the 18 to 49 age group, more peopled watched cornhole on that day than the competing game coverage of Major League Baseball, the WNBA or the final stage of the Tour de France, according to Sports Media Watch.

For Henderson, cornhole requires 20 hours a week of training and tournaments on weekends. Still, he said most people don't take him seriously when he says he plays professionally.

"They'll say, 'Oh yeah really?' and just change the subject," he said. "When people were seeing me on ESPN, everyone's attitude changed."