first sex toy

Im 15 years old and got myself my first vibrator at spencers. I never owned one before and Im confused.

1. How do I cover up the sound? Its pretty loud and I have thin walls and my family are light sleepers so how do I cover the sound up?

2. How do I get my mom to get me batteries for it when it dies? It needs watch batteries and I dont own a watch so she'd question it. My friend got me the vibrator and not batteries for it so idk. Any excuses I could use?