What do sharks and ice cream have in common? Give up? Ask Rita and Mark McCabe. They’re the owners of Sub Zero Nitrogen Ice Cream, which recently moved into the sweet spot of the historic Panagoulas building, at the corner of Water and Main streets. They opened their inaugural and successful Amherst Street location seven years ago, and are excited to be part of the vibrant Downtown Nashua community. In addition to the 83 Main Street store, the McCabes also have a store in Worcester, Mass., with a second on the way in that city, as well as in Cambridge, Mass., and here in the Granite State in Manchester. They are also the New England regional managers and area developers for the company. You’d think managing those stores and determining future local franchisee acceptance would keep them busy enough. But Rita McCabe tells us they also have a very robust events schedule, bringing Sub Zero’s unique nitrogen-frozen ice cream to weddings, reunions, corporate events, mitzvahs, and other catering needs. They’ve also partnered with Fright Kingdom on Simon Street for several “chilling” events there, too.