To "get all ___" means to show too much of an emotion:
There's no need to get all angry about it. I was just trying to help!
She's at an age now where she gets all embarrassed whenever I say anything to her friends or classmates.
These sentences mean the same thing as they would without "all", but "all" helps to show how you feel about the person's emotion. It shows that you think this level of emotion is too much and not needed.
This phrase is mostly used in casual spoken English.