OK, you know the rules, and if you don't I'm going to tell you them anyways, so feel free to pretend like you knew all along. Most folks won't notice anyways.
Fill in the first two panels, you can use any character/background/etc. that you feel is appropriate. In the third panel, the only things you can change are the character on the left (well, you can ADD a character on the left), you can give that character dialogue, and you can (and probably should) fill in the blanks in the character's dialogue on the right. Here's the template:
[Click to view comic: 'BTC 71 Template']
Go nuts!
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"He was cursed with a horrorshow of a face, like Guiseppe Archbold doing a study of mollusk tumors."