Well, a real tongue-in-cheek paper on time travel.
It's interesting to me how staid the journals have become; Einstein famously explained relativity with a "mock paper" published in the Journal of Exothermic Science and Technology (yuk yuk yuk):
I took the train to New York City to meet with Miss [movie star Paulette]Goddard at the Oyster Bar in Grand Central Terminal. She was radiant and delightful. When it felt to me as if a minute had passed, I checked my watch to discover that a full 57 minutes had actually transpired, which I rounded up to one hour. Upon returning to my home, I plugged in the waffle iron and allowed it to heat up. I then sat on it, wearing trousers and a long white shirt, untucked. When it seemed that over an hour had gone by, I stood up and checked my watch to discover that less than one second had in fact passed. To maintain unit consistency for the descriptions of the two circumstances, I rounded up to one minute, after which I called a physician.
Several scientists also publish science fiction; Geoffrey Landis is at NASA-Ames and knows entirely too much about black holes. Charles Sheffield was the chief scientist for EarthSat. Martyn Fogg is probably the world's foremost expert on terraforming whose most famous paper was published in Analog Magazine. It does make you wonder whether or not there needs to be a little room for letting your hair down. Possibly the best aspect of Scientific American is Mirsky's "Antigravity" column, which gets humorous with science, and Analog's "Probability Zero" section is where some of the best conceptual stuff shows up.
Max Tegmark, in "Our Mathematical Universe," describes his mainstream-to-crackpot ratio of paper production and how he only gets into the weird cosmology stuff when he's had a good enough run of dry mathematical stuff to let him skate without endangering his tenure. Perhaps that's the difference: we expect our scientists to do their populist stuff out amongst the hoi palloi while the journals are necessarily reserved for hard science.