I'm going to talk shit about someones birthday gift to me
Why will you be talking shit about a birthday gift?
They didn't know what I like, They got me something I don't like. If you knew about the person, you would understand it.
You are behaving rudely and you are being ungrateful. When a person gives a gift, it is appropriate to be grateful and thankful. You will be losing your friends if you do not appreciate their efforts.
They will get over it. They'll see how much the gift means to me when I talk shit about it.
If you talk badly about your gift then they won't see your point. They would be upset and not be your friend anymore.