Using a Qtip or small brush, add clear corn syrup around the rim of your glass.
Add colored sugar, one color at a time, to a plate and dip a section of the glass rim in the sugar to coat it. You should have all three colors in different sections around the rim.
Depending on the size of your glass, add 2-3 scoops of ice cream.
Now pour your King Cake Soda on top, letting it bubble up.
Fill to the top, add a straw, and enjoy your festive drink!