Purposeful, sarcastic misspelling of "internet". A term seemingly inspired by Something Awful creation Jeff K, known for his indecipherable ramblings patterned after the habits of a stereotypical AOLer.
You can't check your e-mail? Is this your first day on the intarweb, or what?
Tongue-in-cheek reference to the Internet.
Etymology: Bastardized version of "InterWeb", which is a combination of Internet and the Web (which is in turn colloquial term for "World Wide Web")
Urbandictionary? It's one of those things on the intarweb, right?
Literal: Internet
Usually used in a sarcastic method, it is also used to tease internet-illiterate people and other people who cannot speak simple english. I've usually thought of this as a combination of intranet and world wide web, an intranet being similar to the internet, but it is shared on a LAN rather than the WAN.