Drip some of the food writing gel on the inside of the glass to look like dripping blood.

Fill the glass with ice. Then fill the glass about ¾ full with soda.

Fill a 1 ½ ounce syringe with grenadine. Squirt a little grenadine into the bottom of the glass. Place the partially filled syringe in the glass as a garnish and to add more grenadine if desired.