How to mess up the internet connection?

I was wondering if there's any way that I could make my internet stop working? My 9 year old little brother is literally, I'm NOT Exaggerating this, is on the computer from the time he gets home from school until my dad forces him to get off! I honestly think It is making him stupid. When he's on there watching stupid minecraft videos you litterally have to scream at him to get his attention. And if you give him something while he is watching it, he will not even remember you giving it to him. My mom really allows him to be on it for so long! This little boy is on the computer more than I'm, and I'm getting a degree in computer science! I need a way and not just a simple unplug the Ethernet cable, but actually the thing that will show the little yellow triangle with a "!" In it. I was thinking of changing the IP address to some weird number but I'm afraid it will mess up the connection entirely. Any suggestions? Please and Thank you.