The signs and those who are capable of knocking off the principal's toupee:
Aries: knock it off willingly
Taurus: do it because of a dare
Gemini: knock it off when they are first introduced to the principal
Cancer: they're extra careful around the principal
Leo: knock it off every single time they meet the principal
Virgo: always bumping into the principal resulting it to fly off his head
Libra: it's actually you whom it always lands on once it flies off his head
Scorpio: they have the skill to not bump into the principal
Sagittarius: you've never even met the principal
Capricorn: found it on the ground and then threw it out the window cuz it smelled.
Aquarius: found it on the floor and being the nice person you were you threw it away in order to keep the school clean.
Pisces: who the hell is the principal
