In Sharon's dream world of Harry Barker, a bogon is a "digital creature", an artificial intelligence with a virtual reality avatar. Bogons tend to be relatively harmless, but have a nasty defense mechanism to scare away potential attackers. They tend to distract their opponents with ridiculous nonsense, transforming their appearance into whatever image they think will make their "victim" laugh uncontrollably. As such, the best defense against a bogon is to concentrate on one's greatest fear. Doing so will unsettle the bogon and startle it, forcing it to flee. The caveat, of course, is that concentrating on one's greatest fear is distracting in its own right, meaning such a defense can backfire on the hacker trying to defend himself or herself.
Dwayne Duncan used a bogon as a class exercise in his Defense Against the Dark Arts class. During this lesson, Don Measly defended himself by thinking of a spider. Harry attempted to defend himself by thinking of a debugger, but this startled him into inaction. Dwayne stepped in to defend him, during which the bogon transformed into a dragon. (This was a subtle hint that Dwayne was a Beowulf, in reference to the Old English poem.) After class, Dwayne stated that Harry's choice of a debugger was surprising, and that it possibly indicated that Harry's greatest fear was of fear itself: failure to protect himself and his friends from the horrors of his past.
Bogon Alley is named after the bogon "creature".
Bogons are the analogs of boggarts in Harry Potter. The two creatures actually work in completely opposite ways; boggarts attempt to prey on their victims' worst fears and are thus best defended against with laughter, while bogons are the opposite. According to the Jargon File, a bogon is "the elementary particle of bogosity", "any bogus or incorrectly formed packet sent on a network", or "by synecdoche, [is] used to refer to any bogus thing".