«My name is ‘Sue!’ How do you do! Now your gonna die!!» … This is a line from Johnny Cash’s song A Boy Named Sue. So how do we use it? This greeting is used primarily in formal situations, such as with a first-time serious business or diplomatic meeting, very formal family introductions, or encounter with royalty. It is a older way of greeting someone and traditionally accompanied by with the tip of the hat (for those that wear them!), a nod (moving the head down slightly) or even a gentle bow (very formal as you can imagine!). Note that the greeting is NOT actually a question. It is not the same as ‘How are you?’ and therefore the way to respond is NOT to say ‘I’m fine, thank you.’ Instead you should REPLY with the same «How do you do?» OR one of the following: «Pleased to meet you», «Very glad/nice to meet you», «Delighted to meet you.» Of course, we also use the expression to add humor while giving the impression of a formal greeting, such as in the case of Mr. Cash’s song! Thanks for the great question Chuchi!