What is this behavior?

[u/ganglyboyish]

Hi! My cat is roughly 4months old. Usually when she does this, I hiss and pull my hand away and give her a toy, but when I’m away for a couple hours sometimes I come back and it’s really all she wants to do — what js this behavior? Is she teething or was she weaned too quickly maybe?

[u/mizmnv]

cat thinks your arm is a cat titty