I swear this question comes up often enough to warrant it. The first time a user goes to ask a question a page should come up mentioning at least the topic of parsing HTML with regular expressions and possibly others (eg writing compilers) that are common to the point of being absurd. Don't disallow the user from asking it but just make them look at a page that doesn't have too much on it other than:
If you are going to ask...
- a question about parsing HTML with regular expressions, read this; or
- ...
Ok, if your question doesn't fit in this category press Next
Or something like that.