First things first, the title is a misnomer - it's just a reference to a book that's also not much about Zen. If you've come looking for Zen, you won't find it here. But you might find it here.
Ah, still here? You must have come about the bot-building then...
You were probably expecting something a little more organized? Well, I don't do "organized" much, so you'll have to put up with some rambling - until I get round to whipping this page into shape (which may or may not happen any time soon/ever.)
"Leeds" filter:
([bcdfghjklmnpqrstvwxz1234567890]+) (re) will catch "l33t 5p33k" and similar inanities (note: there are no vowels in the character set handled by the regex.) I'm sure you can come up with appropriate responses on your own! You might want to have a higher-ranked keyphrase ([hm]+) (re) to screen out the occasional "hmmm"s which may otherwise incur an overly harsh response.
You can also use regexes to trap the verb stem from eg: a past participle: I was ([abcdefghijklmnopqrstuvwxyz]+)ing (re), which (assuming a regular weak verb) you can then use in a response, eg: you really (key1)ed? You'd probably need to screen out a few dozen common strong verbs with some higher weighted keyphrases to avoid childish mistakes ("I singed", "you goed", etc.)