Using a shallow bowl filled with water, soak toothpicks for at least 1 hour to prevent buring.
In a small saucepan, combine the beer, onion powder, garlic powder, cayenne pepper, and brown sugar. Bring to a boil and reduce heat to allow the mixture to simmer.
Simmer for about 20 minutes until the mixture reduces to half and thickens.
While the mixture is cooking, preheat your grill to 400℉. Skewer each sausage and pineapple with a soaked toothpick.
Place each sausage and pineapple on the grill and brush with the beer sauce. Using tongs, rotate the sausage and pineapple skewers on each side. Continue to brush with the beer mixture until done, about 8 minutes total.