Ways to hide my lip piercing?

Okay so I got my lip done like, six weeks ago now, and since I got it done the school have not stopped pestering me about it. I'll be walking down a corridor and some teachers will call me over and say something like "You do know you're not allowed facial piercings in school?" and I always say "Yeah but I'm expressing myelf" and walk off. I can't stand it anymore! I don't want to take it out, because I tried that, it was only out for an hour and it closed up, I had to re-pierce it myself. And I'm not walking round with a plaster on my face either.. I need ways to hide it from the teachers, 'cause I'm sick to death of them making such a fuss over it, it's only a tiny stud. Thanks in advance :)