"Beer spikes" - ever heard of them?

Legend has it that "beer spiking" dates back to the Middle Ages and was invented by blacksmiths. They were able to carry out their trade outdoors even in winter, as the forge radiated enough heat and was therefore warm enough. However, the beer in the bucket next to it ran the risk of freezing over - something an Innviertler couldn't risk: that's why the resourceful blacksmiths repeatedly dipped or spiked the red-hot poker into the beer. Beer spiking" was invented.

And it still works the same way today
Take an iron rod, heat ...