I accidentally told my sister in law that people with her major are terrible
Oh no. How did you accidentally tell her that?
I've been saying that people with her major are stupid all along, but I accidentally mentioned it while she was around.
Every field of study is important in some way and has a reason to be there. Generalizing about the way someone is by their major only makes you look like the bad person. Be kind and things will still be okay.
I'm right and you are wrong. College students are stupid.
I'm sure you think you are right and you have your own opinion. You just need to keep an open mind, you could be wrong too no matter how right you think you are.