Girl's Behavior

What does it mean when a girl keeps flicking my arm?

When it's just us two or when we're watching something in a group, she would continuously flick my arm despite my attempts to motion her hand away. I tried flicking her thigh to see if she reacted, and she told me that she didn't mind. When I tried to pinch her cheek, she grabbed my hand and motioned it away

Why is she flicking my arm? Why did she react differently when I clicked her thigh vs pinching her cheek?
What does it mean when a girl keeps flicking my arm?
Post Opinion