Nessie is actually a cyborg
created by the Zygons" is not an appropriate thing to say in Care of
Magical Creatures Class. 

I will not ask the school to
sponsor a breakdancing group

Nearly HeadlessNick does not
approve of being called Casper the Friendly Ghost

The Giant Squid is not to be referred to as 'my lord
Cthulhu', nor am I allowed to sacrifice first years to it on the new moon

Thestrals do not resemble
the muggle toys known as 'My Little Pony'.

I am not allowed to scare
the first-years by screaming "I'm melting! I'm meeeeeeeeeeeltiiing!"
while they are in the showers.

Enchanting the Sorting Hat to sort new students into the House of
Martok, or any other Klingon house is forbidden.