Preheat the oven to 375 degrees F. Lay out the pancetta onto an ungreased baking sheet. Place in the oven and cook the pancetta until extra crispy, 18 to 20 minutes. Remove and let cool.
For the tomato-arugula pesto: In a dry skillet over medium heat, lightly toast the pine nuts until slightly golden, 3 to 5 minutes. Remove and set aside to cool.
In a food processor, add the toasted pine nuts, arugula, basil, cheese, sun-dried tomatoes, lemon juice and garlic. Pulse until just combined. Slowly stream in the olive oil until the pesto has a nice rustic consistency, about 10 seconds. Season with salt and pepper.
For the sandwich build: On the bottom of a slice of challah, schmear a bit of mayo and then top with some of the turkey slices and a piece of lettuce. Schmear pesto on both sides of the second slice of challah and place it on top of the lettuce, and then more turkey and then some of the pancetta. Schmear mayo on the third challah slice and top off the sandwich. Use a toothpick to skewer the layers together. Repeat with the remaining ingredients.
Cut it into quarters, tip the D.J. to play your favorite jam (R-Kelly's Ignition [remix]) and get to Clubbin'.