system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] What does "Abracadabra" do?
gpt
Fun Fact. In the wizard Community, "Abra Kadabra" is the linguistic equivalent for "Duh" in Muggle culture, as something you would say when someone else said something incredibly stupid. 

A number of years ago, some young Wizards used their magic to perform what would look like Ordinary Magic tricks to Muggles, presumably for quick cash. And as a joke, they used words like "Hocus Pocus" and "Abra Kadabra" in place of regular incantation. The phrase stuck around, and that is why Wizards can't bring their younger children to Magic acts in Vegas, otherwise they would burst out into giggles whenever the "magician" would perform a trick.