Make the red velvet cupcakes according to a recipe that will yield two dozen. A normal cake recipe should suffice.
Once they have cooled, smear the tops with rose syrup.
Cream the butter and cream cheese together until well-blended.
Add 4 cups of the powdered sugar and the vanilla extract.
Set aside some of the frosting for decorating the tops of the cupcakse.
Add the black food coloring to a portion of the frosting, and set aside enough to frost the tops of the cupcakes. You'll half mostly black and a little white frosting for your design. (See photo above).
Add the Campari and the rest of the powdered sugar to your original butter/cream cheese/sugar mixture. It will be liquid-y, but add more sugar if it gets too runny.
Spoon the poison filling into a plastic bag fitted with a clean anal douche pipe. (e.g., enema or douche bag).
Use the pipe to inject the cupcakes with the poison filling. (See photo at left).
You make need to poke several holes, but be careful not to fill the new holes too quickly or the frosting may blort out the preexisting ones.
Once the cupcakes are sufficiently "poisoned," frost and decorate as desired.
When your guests have complimented your cupcakes, be sure to let them know how they were made. Enjoy the priceless entertainment.