Why did she make me apologize?

[eeeeeeeeeeeeee]

Recently, when I was in the car and my mom was the driver (she was about to take me to school) before she started the car, she asked me to pray out loud for a safe trip. I'm not really a believer, but my mother is. Bad things were happening to me a few years back, and God didn't help me, so that's part of the reason why I'm no longer a believer. (also I began to study science) And as my mother asked me to pray, I was thinking about a joke about Jesus. So as I was starting to pray, I started laughing. My mom made me pray all over again. I tried again, but again I began to laugh when I was starting to pray. This happened like 2 more times. I couldn't control my laughter at that time. When I was finally able to pray out loud without laughing, my mom said, "Now say you're sorry." I said, "I didn't do anything!" Why did she ask me to apologize??