She took her dad for a chump. She tried to pull off a trick where she pretends to move a quarter from under a water bottle to the inside without touching the bottle. When the "audience member" gets their face close to the bottle at the end to inspect the trick, the bottle is squeezed, shooting water into their face.
Her dad wasn't having it.
It's not clear if he knew all along or if her "magic magic magic" incantation tipped him off that he wasn't dealing with David Blaine. Either way, he got her before she could get him. In doing so, he launched what might be the greatest dad-burn to have ever graced the internet: "You think I don't watch internet?"