Is there supposed to be a comma used between the words Yes sir?

Yes, a comma is typically used between "Yes" and "sir" when addressing someone directly, so it should be written as "Yes, sir." This comma indicates a pause and clarifies that you are responding to the person. However, if "yes sir" is used in a more casual context or as part of a sentence, the comma may be omitted, but in formal writing, it's best to include it.