class-name-filter/profanityfilter.py

import builtins

_original = builtins.__build_class__

naughty_list = 'pony', 'ponies'

def profanity_filter(func, name, *args, **kwargs):
    if any(bad_word in name.lower() for bad_word in naughty_list):
        raise RuntimeError('Disgusting! Thats how you name your classes?!')
    return _original(func, name, *args, **kwargs)

def disallow_profanity():
     builtins.__build_class__ = profanity_filter

def allow_profanity():
     builtins.__build_class__ = _original

disallow_profanity()