You have presented a funny situation, not a funny comic. Funny situation: Someone sees his friend looking at porn and realizes its his sister on the screen. But turning it into a comic requires you to add a zing at the end, a sort of "punch line" if you will. See what you think of this:
[Click to view comic: 'Reworking Comic 476411']
The punchline is punchier, making it a better comic. It is also gramatically correct, for people who care about that sort of thing. (A lot do).
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peddling the funny around since 09/24/2002