Using a pastry brush, brush the rims of two glasses with chocolate syrup. Crush 2 sheets of graham crackers and place them on a small plate. Roll glasses in graham cracker crumbs.
Place chocolate ice cream, milk, bourbon, 4 sheets of graham crackers, and ten marshmallows in a blender and blend on high speed until combined. Divide milkshake between two glasses.
Top with whipped cream and rainbow sprinkles. Put marshmallows on skewers as garnish and add a sheet of graham crackers into each milkshake.