Make a boxed cake as directed on the box and allow the cake to cool completely. Once the cake has cooled, cut it into small pieces and place them in a large mixing bowl. Break up the pieces with a spatula or your hands to get small crumbles.
Take ¾ or the entire can of frosting and mix it into the crumble mixture (I find ¾ is plenty but you can go all in too). This takes a little elbow grease to get it all mixed in. The mixture will be similar to dough.
Prepare a cookie sheet with wax paper. Scoop out 1 ½ tablespoons of cake mixture and roll it into an oblong-shaped ball between your hands (this is easier if you spray your hands with non-stick spray). Form a ghost shape on your hand and place it on the wax paper. Continue to make ghosts with the rest of the mixture. Don't worry if your ghosts are perfect, they look spookier if they are a little messy.
After shaping the cake pops, chill them in the refrigerator for at least 30 minutes. This helps them firm up and easier to dip in the candy coating.
Melt the vanilla candy coating in a microwave-safe bowl for 45 seconds. Stir the coating and continue to melt at 20-second intervals until fully melted. You can also use a double boiler on the stove. Add the vegetable oil to thin out the coating slightly.
Using a spoon, pour the melted candy coating over the top of each ghost coating them completely. You may need to use a few spoonfuls to get the ghost completely covered. Repeat with all of the ghosts. If your candy coating starts to thicken, place it back in the microwave for 20 seconds to soften it again.
Once coated, make a face on each ghost with the writing gel. Get creative or make them all the same.
Allow the ghosts to set completely before enjoying them (you can speed up the process in the fridge).