In a small saucepan, combine brown sugar, mayonnaise, and chili sauce. Cook and stir over medium heat until mixture cones to a boil; set aside. Place a water chestnut and pineapple chunk on each slice of bacon, roll up bacon and secure with toothpick. Place on broiler pan and broil 4-5 inches from heat. Broil 4-5 minutes on each side or until crisp. Serve with sauce. Makes 14 appetizers.