Not really hacking, but my roommate says otherwise. So we share a router in the apartment and I’m the only one that really knows how to access it, so of course I change the password and tell no one (not like they’ll try to get in anyway).
Occasionally set roommate likes to get blackout and play music very loud at 2am. To be petty, on those occasions I set up an RPi Zero to connect to the WiFi, restart it, and sleep for a minute, and repeat. He’s still convinced we are getting DDOSd, and suspects nothing.

Reason I don’t just set parental controls - he gets more frustrated when the WiFi appears for 10secs, the music is just about to start and shuts off again. So he gives up quicker. Otherwise, he resets the router and I have to set up everything from the start.