Pople who are incapable of saying "bye" just once at the end of a hone conversation.
You know the type - so morbidly insecure that they have to say "bye - bye" in a horrible, tremulous falsetto, as if unsure if the other person heard them.

It drives me mad! - it is not even a "bye bye" said close together, but with a noticeable pause and then a gabbled second "bye".

Just say it once and be done with it for fecks sake!
(brumguvnor www.twitter.com/brumguvnor, Sun 4 May 2008, 14:29, Reply)