Well, it seems we're getting a better idea of what Millar wants in his magazine. He didn't give us much to go on, so it was hit or miss. I notice the forum members posted submissions that were closer to FutureShocks, and clearly he didn't want
FutureShocks...I suppose a couple of those winners could be deemed to have "twist endings", but as Colin said they are all a bit light on story (and calling the planet "Pee Pee" sort of gave that particular twist away).
So now we have a better idea of what he's looking for - potty humor, by and large! - so one of us will just have to get in the hard way...

. ...now I'm off to mail off my submission to Mad Magazine!
Edit: I should clarify that I don't find any of these "bad"; they are enjoyable for sure!