Time for psychological warfare. Use whatever you want:
1. Next time you see your parents, sing the most disturbing line of a song you know. (Maybe don't use that actually.)
2. Say vaguely threatening lines, like "Enjoy the next 24 hours of your life!"
3. When texting them, say "worm regards" at the end of every 10 or so texts.
4. Walk sneakily for no reason when you know they're watching.
Basically, do mildly questionable things once or twice a day to meet one of these goals:
-Drive them insane, very gradually.
-Make them become used to gradually more questionable things, and make yourself seem normal enough to them that they punish you less or not at all.