Brush inside of a piping bag with food colouring.
Spoon buttercream icing into prepared bag
Pipe dollops onto cones and serve.
Head to your nearest bakery and ask for donuts in the Olympic colours. Or simply get ring donuts and make your own coloured icing. These are delicious, easy and look really cool!
Get little flags on toothpicks and stick them into small sandwiches. You can make them into circles with a cookie cutter or an upturned glass or cup.