PLEASE ANSWER

In class, I silently passed gas and a girl on the other side of the classroom named Nyla eventually smelled it. She complained to the teacher that someone passed gas, but didn't know who. Another girl, named Lia, accused me of doing it cause i was laughing and she had a mean smirk on her face.
3 questions:


1. Why did she have a mean smirk when accusing me?

2. Why did she accuse me?

3. Why did I feel self conscious about my butt after the whole class started laughing