I understand "boy do I" means to add emphasis. But your example sentence sounded like "Boy do I" is one idiom. To be accurate, do I need to use a comma after 'Boy'? And if I wanted to use Oh! or Oh no! instead of Boy, should I say "Oh (no), do I feel bad" or "Oh (no), I do feel bad"? What is the difference between those two?
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Rebecca
Good question. "Boy do I" is an expression but not an idiom. So yes, to be more accurate, you can definitely insert a comma after "boy". You are right about "oh" or "oh no" being another term used for emphasis, however, it is not very common in English to use it in this way in place of "boy, do I", and it would sound a little bit unnatural to do this. Instead you could say something like "Man, do I feel bad" or "Gee, do I feel bad". Ex: Oh boy, am I sorry. Ex: Man, do I wish I could go back to Australia. If you changed the placement of "do" in the case of "do I feel bad" and instead said, "I do feel bad", this would change the meaning of the sentence. When "do" comes before "I", it is used for emphasis in a question form although it is not a question. If you said "I do feel bad", this would sound like you are answering someone else's question instead of making a strong statement. Ex: "Do you feel bad?" "I do feel bad."
