Once the cake is cooled, use your hands or two forks and to crumble the cake into fine crumbs.
Add 3 tablespoons of sprinkles and mix it into cake crumbs.
Put remaining sprinkles in a small bowl and set aside.
Add buttercream and mix with hands or fork until the buttercream is fully incorporated. You want the mixture to be just moist enough to roll into balls.
Using a small ice cream scoop, scoop out a small amount of mixture and roll between cupped hands until you reach the desired round shape.
Put balls on a plate and cover with plastic wrap. Place in refrigerator for at least 4 hours.
Place coating chocolates in a deep bowl so you will be able to submerge the entire ball in the chocolate. Melt chocolates.
Dip the lollipop stick into chocolate and then into the middle of the ball. Let sit for 2 minutes.
Dip the cake ball into the chocolate until it is completely covered. Hold it sideways over the bowl and rotate it and tap it so the excess chocolate comes off.
Use a spoon to cover the ball with extra sprinkles. Make sure the entire ball is covered.
Push the lollipop stick into a styrofoam block or cake pop holder to dry.