I was wondering which one of these two sentences is more common:
1)Can I help you, sir?
2)Can I help you, mister?
I always thought that mister, actually the abbreviation form (Mr) is only used before family names like Mr. Smith, and it's not common to use mister in occasions like example (2) and we use sir alternatively; however, I came across an example in Longman Dictionary:
Which sounds a little bit odd to me.