Prepare cake mix as directed on package, adding vanilla to batter.
Bake as directed on package for cupcakes. Cool cupcakes on wire rack.
Frost cupcakes. Place a ring-shaped candy or sliced gum drop in the middle of each cupcake for the iris. Attach a candy-coated piece with some frosting for the pupil. Place small amount of red food color in a disposable paper cup. Using a toothpick, draw “bloodshot” lines in the white frosting. Or, tint any remaining white frosting red with red food color. Spoon frosting into small resealable plastic bag. Snip a small corner from bag. Pipe frosting to create the bloodshot lines.