Grease an 7"x11" pan with butter. I like to leave it as a stick and rub it across the pan and partway up the sides. If you don't have a 7"x11" pan, you can use a different size, but the thickness of your hokey pokey may vary depending on the surface area available.
Measure out the 2 tsp. baking soda and set aside in a small dish.
Add the 4 Tbsp of golden syrup, and 10 Tbsp of sugar to a medium pot and heat over medium. Stir continuously until sugar and syrup have dissolved.
Simmer for 5 minutes, or use a candy thermometer to check the temperature reaches 145-150°C (293-303°F).
Immediately remove from the heat and add the 2 tsp baking soda. Stir vigorously as the mixture foams and bubbles, and as soon as the baking soda is fully incorporated, pour into the prepared pan.
Do not touch the liquid sugar as it sets, as it is extremely hot and will stick to your skin and badly burn you. Allow to cool for at least an hour, up to overnight.
Break the hokey pokey into pieces. It's very brittle and will break on it's own when dropped on a hard surface. I recommend dropping it in a pot with sides to contain the brittle pieces and make for easier cleanup.