Preheat oven to 350°F (175°C).

Cook bacon in a large skillet over medium heat until almost crisp.

Drain excess grease from the bacon.

Wrap each water chestnut with a half slice of bacon and secure with a toothpick.

Place the bacon-wrapped water chestnuts in a baking dish.

In a separate bowl, mix together mayonnaise, brown sugar, and chili sauce.

Pour the sauce mixture evenly over the water chestnuts.

Bake in the preheated oven for 45 minutes, or until the bacon is fully cooked and the sauce is bubbly.

Serve immediately.