At the heart of Halloween are costumes (and candy), so invite everyone to wear their favorite costume to your kids bowling party. They can wear the outfit they plan to wear on Halloween, or you can ask everyone to dress according to a theme, such as their favorite superhero, monster, or sports player.
Make the party even more fun by having everyone act “in character” during the party. Just imagine how fun it will be to watch Darth Vader try to use the Force to guide the bowling ball down the lane, or listen to a monster roar with joy at a good score.