In a medium bowl, whisk together the teriyaki sauce, brown sugar, ginger, garlic, salt, and pepper. Pour half of the mixture into a separate bowl and set both bowls of sauce aside. One will be used to baste the ingredients before grilling; the other will be used to baste the cooked skewers before serving.
Wrap each piece of scallop with one half of a bacon slice. Thread the bacon-wrapped scallop onto a skewer so that the skewer helps hold the bacon in place. Then thread one piece of pineapple. Repeat the process again, so that you have two sets of bacon-wrapped scallops plus pineapple on each skewer.
With a pastry brush, baste both sides of the skewered bacon-wrapped scallops and pineapples with teriyaki sauce from one of the bowls. Wash and dry the pastry brush and put the remaining teriyaki sauce from that bowl away.
Grill the skewers, uncovered, on medium-high for 3 to 4 minutes per side. When the skewers are done cooking, use the remaining bowl of teriyaki sauce and baste both sides of the cooked skewers with a nice thick layer of sauce.
Notes
GRILL TEMP: When grilling medium-high heat, your grill should be between 375°F and 450°F. I like to do one test skewer first in order to adjust and set the right temperature. Remember that every grill is a little different, so a test skewer can help ensure even cooking for the remaining skewers. SCALLOPS: Make sure you use sea scallops and not bay scallops. Bay scallops are too small to cook on skewers.BACON: choose bacon that comes in wide slices and be sure to stretch each half as much as possible to wrap around each scallop.