[from the `surf' idiom for rapidly flipping TV channels] To traverse the Internet in search of interesting stuff, used esp. if one is doing so with a World Wide Web browser. It is also common to speak of `surfing in' to a particular resource.
Hackers adopted this term early, but many have stopped using it since it went completely mainstream around 1995. The passive, couch-potato connotations that go with TV channel surfing were never pleasant, and hearing non-hackers wax enthusiastic about "surfing the net" tends to make hackers feel a bit as though their home is being overrun by ignorami.