Inflate 4 small balloons to desired size. Line a baking sheet with parchment paper. Set aside.
Set up your station: Place rainbow sprinkles in a large bowl. In another large, microwave-safe bowl, heat chocolate chips in 30-second intervals until melted and smooth. Working one at a time, dip the bottom of the balloon into the melted chocolate, rolling it around to make sure all sides are evenly coated. Quickly roll the balloon into the sprinkle bowl, making sure all of the chocolate is coated. Place on parchment sheet to set for at least 1 hour. Repeat to make 3 more balloon bowls.
Once fully set, pop balloons and remove to reveal bowl. Serve with ice cream.