I was being rude to my classmate and threw away my birthday gift from her.
Why did you decide to throw out the gift?
I was mad and I wanted to just throw the gift away so I don't have to think of her.
It is wrong to throw out a gift. You may not get gifts from people again.
I don't care, I just bought a new bike and threw the one she gave me.
There might be a difference between the two. It is rude to not appreciate a gift. Your classmate was being kind and didn't have to get you anything at all.