Worse still is abbreviating someone's name without permission.
I loathe this. I had a flatmate who did this constantly - sometimes upon meeting people for the first time - and doing it literally immediately after being introduced. It used to make me weep with rage.

'Scott, this is David'
'hi Dave'

He was from Birkenhead*.

*Scott, I mean- 'Dave' is someone I made up for illustrative purposes.
( Monty Boyce, My cheese game is strong, Mon 5 Sep 2011, 15:29, 2 replies, latest was 14 years ago)

Yeah Mont, you tell 'em

( sporters I’m sincerely gratitude to you, Mon 5 Sep 2011, 15:34, Reply)

People do this to me all the time.
Even worse because the contraction of my name makes me sound like a fucking hairdresser.
( Kroney, Mon 5 Sep 2011, 15:43, Reply)

I like how your sig mentions Jamaica, and then it says, Mon after it.

( Vipros. clever got me this far, then tricky got me in, Mon 5 Sep 2011, 15:44, Reply)

I like this as well.

( Davros' Granddad a voice of calm reason in a world of spastics., Mon 5 Sep 2011, 15:47, Reply)

God, of course B3ta's own ganja smoking Rastafarian surfer would pick up on this.
How is Jah, these days?
( Kroney, Mon 5 Sep 2011, 15:47, Reply)

he's all the better for you asking after him

( Vipros. clever got me this far, then tricky got me in, Mon 5 Sep 2011, 15:56, Reply)

Most people are.

( Kroney, Mon 5 Sep 2011, 15:57, Reply)

Cool story, Kro.

( Monty Boyce, My cheese game is strong, Mon 5 Sep 2011, 15:47, Reply)