I came across a sign in the "TSA pre-check" lane at the airport today that said "Keep those shoes on. You busy traveler, you.":
There are three things here that caught my eye. First – "those" shoes, rather than "your" shoes. Second – the period after "on." – it seems that it is not needed. Third – "you traveler, you". I am familiar with the usage, but don't know what that construction is called, nor what effect is the author is trying to achieve with it? It feels to me they are trying to be lighthearted. Is that correct?
A bit of context for people outside of the USA: the TSA "pre-check" lane is a fast lane for "trusted travelers". The benefit is that you get to keep your shoes on (in the regular check, your shoes go through the Xray), you don't have to go through the body scanner (just metal detector), and don't have to take your laptop and liquids out of your carry-on. When you are in a hurry, that does save a few seconds.
PS – earliest hit found on Google for "you busy traveler, you" is from December 2, 2013 in a tweet by TSA
Best Answer
Let's take each of your points one by one.
(1) "Those shoes" versus "your shoes"
Both are grammatically correct. "Those" shoes changes the tone. It is not true that using "those" instead of "your" always makes the tone more lighthearted, but in this example that's exactly what it does; it makes the tone more playful. It does this by making it less accusatory. Saying "your shoes" implies that "you" are responsible (and thus at fault if you fail to comply). "Those" redirects the blame elsewhere and thus makes it less likely to put the reader on the defensive.
(2) Period after "...shoes on."
You are correct; the period is not necessary. "Keep those shoes on." is a complete sentence, but "You busy traveler, you" is not a complete sentence. By omitting the period after "...shoes on", you now have one longer sentence: "Keep those shoes on, you busy traveler, you." With that being said, on a large sign/poster like this, grammatical correctness is not necessarily of greatest significance. The author likely chose to use a period for emphasis, to enforce a larger pause, or even just because it looked better visually. While this wouldn't be appropriate in formal writing, greater creative license is granted to signs and other short form writing like this.
(3) "You busy traveler, you."
Adding the "...you" at the end definitely increases the playfulness. It's meant to be jovial and playful.