Interweb (sometimes deliberately misspelled intarweb(s)) is a sarcastic term used to indicate inexperience by intentionally and incorrectly merging the Internet and the World Wide Web. The joke is that the correct casual name for the World Wide Web is "the Web," which is part of "the Internet," and content found on the Web can be said to be either "on the Web" or "on the Internet." "Interweb" implies a naive confusion of these two terms.
The term interweb originated as the hacker culture response to the ever-increasing influx of inexperienced users to the Internet's forums and chat rooms. Whereas the Internet had previously been the exclusive domain of the tech-savvy, it was now attracting millions of newcomers (newbies) who were now participating in it (often with poor netiquette). Referring to the Internet as the interweb mocks the inexperience and ignorance of these newcomers, whose lack of understanding of the workings of the 'net would often amuse or annoy the more experienced.
The term interweb is also used in an ironic or post-modern manner by those who understand the full meaning and implications of the word.