[UK, perh. originally from the first Roger Irrelevant strip in VIZ comics, spread via Your Sinclair magazine in the 1980s and early 1990s]
1. n.,v. Commonly used to describe chatter, content-free remarks or other essentially meaningless contributions to threads in newsgroups. “Oh, rspence is wibbling again”.
2. [UK IRC] An explicit on-line no-op.
3. One of the preferred metasyntactic variables in the UK, forming a series with wobble, wubble, and flob (attributed to the hilarious historical comedy Blackadder).
4. A pronunciation of the letters “www”, as seen in URLs; i.e., www.foo.com may be pronounced “wibble dot foo dot com” (compare dub dub dub).