This is a very festive drink! Our sons were offered these at a family-friendly pub we visited recently and they were super-impressed! Am recreating it here using the method the bartender taught me. It's a bit fiddly to make and sugary as all hell but fun nonetheless.
Green food colouring
Fill a glass with orange juice
Add some ice
Use a straw to pour raspberry cordial directly into the bottom of the glass. I used a bottle pourer to pour the cordial down the straw. If you don't have one of these try putting the straw down into the cordial bottle then covering the top of the straw with your finger before quickly transferring it into the glass of orange juice and releasing the liquid. You may have to do this a few times to get a deep enough layer of red. The cordial is thicker than the OJ and therefore heavier so it stays sitting on the bottom of the glass.
Add a few drops of green food colouring to the top of the glass and gently stir it around with a toothpick.
Voila! A Traffic Light!