I have a terrible habit - and one that seems to happen unconsciously - of copying a person's accent.
So if I'm talking to a Yorkshireman I'll adopt the northern accent, if I'm talking to someone camp I'll get very theatrical, and if I'm talking to a Pakistani I sound like Peter Sellers.
Oh yes I forgot to mention that I copy the accent badly.
When I realise I'm doing it I make an effort to stop but I fear I could offend a whole load of people before that. So if I've done it to you please refriend me! I'm sure it must be some subconscious urge to make the other person feel comfortable. That's what I tell myself anyway.