The new spot opens with the actress dancing in a parking lot as she puts a paper bag over her head in preparation to rob a fast-food restaurant.
McCarthy's character robs the restaurant, taking with her some money and pies.
She then appears to go on a cross-country trip with her grandmother, played by Susan Sarandon, as a fugitive of the law.
Tammy opens in theaters July 2.
Swim Week Miami Beach 2014 [PHOTOS]