My second entry for the
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Soo this has a bit of a story behind it. I couldn't leave well enough alone xD
Basically my head cannon is every year North would have a party on Boxing Day for a successful Christmas and it's Jack's first time going to one. He drinks crap loads of chocolate milk (thus the mustache) gets a sugar rush and starts picking Sandy up and dancing around with him. Suddenly, Tooth decides to point out that Jack has danced them all the way to under the mistletoe. Embarrassing events happen.
Also, the sweater is different because Tooth made him wear an ugly Christmas one xD