According to the joint research of the major Kashrus agencies all Slurpees are kosher and Parve except the following:
Barq’s Brand: Caffeine-Free Root Beer (kosher only when bearing O/U)
The following flavors are kosher – Dairy
Fanta : Banana Split and Pina Colada are both dairy, Cholov Stam)
Jolly Rancher: (Note: All Flavors are Dairy, Cholov Stam)
Yo Cream: (Note: all flavors are Dairy, Cholov Stam)
Pepsi (Note: Diet Pepsi is dairy, Cholov Stam – Diet Pepsi Soda is Parve)
The following Slurpee flavors are NOT Kosher:
Horchata Ole – Not Kosher
Orange Barq Smoothie – Not Kosher
Strawberry Twizzler – Not Kosher
Monster Black – Not Kosher
Tropicana Grape Wild Strawberry – Not Kosher