Because I wrote a story a while ago where I referred to character a giving character b a head job, which is very common slang in Australia. And I just got this reply, but the person was anonymous so I can't reply to them;
"very good but its not a 'head job' its either a 'head' or a 'blow job' really good though"
Edit: Wow, thanks for the super quick replies. I'll have to put something in my story notes about it. I didn't realise that it was such an uncommon term. The more you know!