I want to give the middle finger to my dad.
Are you serious? Why do you want to disrespect your dad like that?
He's a bad person, and he always puts others down.
Respect is a two way street, and showing parents that you appreciate their efforts demonstrates a level of respect towards them. If you have issues with your dad, talk to him and communicate so that you can get on the same page.
You don't know my dad. He's the worst and he'll never change.
You might be surprised at how much people can change. If you talk to your dad about how you feel, he might see that he's in the wrong and work to be better.