Reserve 1/4 cup of Teriyaki sauce and refrigerate until ready to use.
Remove the bacon from the package and while it's still all stuck together, stretch it out a little (lengthwise). If you're using center-cut bacon (and the "slab" is not as wide as regular bacon), just cut it in half. Otherwise, use kitchen shears to cut the slab into thirds. Place in a large pie plate or 9x13" baking dish.
Using kitchen shears, cut chicken into bite-sized pieces. You can gauge about how many pieces you'll need by how many pieces of bacon you have--count the slices of bacon and multiply by 2 or 3 (depending on how many pieces you cut the bacon into) and then aim to cut about that many pieces of chicken. Add the chicken to the bacon, then add pineapple and cover in Teriyaki sauce. Cover and refrigerate for 8 hours or overnight.
When ready to cook, wrap each piece of chicken in a piece of bacon and skewer. Top with a chunk of pineapple. For appetizers, you can make these on toothpicks; for skewers, alternate bacon-wrapped meat with pineapple (3-4 per skewer).
Preheat grill to 375-400. When hot, place skewers on grill and baste with reserved Teriyaki sauce. Cook about 7 minutes and flip skewers. Baste again and cook another 7 minutes. If grilling appetizers, use a grill pan if necessary to prevent them from falling through the grates.
To make these in the oven, line a baking sheet with aluminum foil. Preheat oven to 400. Place skewers on baking sheet and and bake about 20 minutes, turning once, following the same basting instructions.