Wrap the bacon around the pieces of tuna and secure with toothpicks. Fry in a nonstick pan or wok over medium-high heat on all sides until the bacon becomes crispy. Remove from the pan and discard any excess fat. Add the barbecue sauce and orange juice. Add the reserved bacon-wrapped tuna bites to the pan and continue cooking until the sauce thickens, about 5 minutes. Serve warm.