(There will be rampant male shirtlessness. Just a friendly warning, or an invitation, depending on your tastes.)
It’s a Zippy strip (today’s!). It’s another gender note (about masculinity). It’s yet another shirtless posting (shirtlessness as a prime masculinity display, in fact.) It’s about umliterature (physique magazines, in particular). And about camp (Flash Gordon). And of course, since the arousing shirtless campy musclemen are from Mars (or possibly Mongo), about SF. And finally, tucked in there inconspicuously in the last panel is an antique Griffithian self-referential surprise (from 1973):
(#1)
Male superheroes are extravagant embodiments of masculinity: they are, to start with, embodiments of great human power (conventionally associated with men), and then they have superhuman powers beyond that; their cosumes are designed to encase their bodies, but tightly, so as to suggest, reveal, or exaggerate every bit of gendered anatomy (the broad shoulders, the musculature of the arms, torso, and thighs, and the genital package). (Beyond the powers and the costumes, there are the conventionally hyper-masculine faces.)
The strip begins with superheroes on this planet, but it ends, in the lower right corner, with (hunky) superheroes in space — “Musclemen from Mars” is what the Dingburgers are reading — and it turns out that space-traveling superheroes (as exemplified by Flash Gordon) are given to frequent bouts of shirtlessness (mostly while performing their feats of manly derring-do, but sometimes during the virtually obligatory shirtless torture scenes).
“Musclemen from/of Mars”. A search on these expressions took me in several directions, some of them unexpected.
First, presumably through musclemen, I was led to sites for male revues (for female audiences) in several cities, all using this figure of Pecsy McAbs against various urban backgrounds:
(#2) Shirtless masculinity on display to the max (on the gender significance of shirtlessness, see my 9/28 posting “Gender notes: transgender fashion models”)
The item revue, from NOAD:
noun revue: a light theatrical entertainment consisting of a series of short sketches, songs, and dances, typically dealing satirically with topical issues. ORIGIN French, literally ‘review’ [but distinct in spelling].
So there are Broadway revues. But also male revues, which are only minimally structured. From my 7/1/19 posting “Oh Canada, baby, ripple my maple leaves!”
Male revues.The more refined term of art for the performances of male strippers, referring to male striptease shows — for audiences of women or of gay men. The performances range from no-contact shows emphasizing professional choreography and playfulness — as in the Chippendales’ shtick for women — down to raunchy foreplay to actual sex, as in what was available for gay men until last December at the Nob Hill Theatre in San Francisco
Second, presumably through the combination of musclemen and Mars, I was led to the pocket-size men’s physique magazine Mars (which exploited the symbol 
representing the Roman god Mars, the planet Mars, and the element iron, and — as the spear of Mars — serving as the biological symbol for the male sex). From the Pinterest site:
(#3) Issue #1 (5/63); just a posing strap, buddy
(#4) Issue #27 (9/67); sniff the leather and sweatThe physique studio Kris of Chicago operated from 1953 until 1976 and was responsible for documenting a huge array of athletic models throughout the period. Co-founded by Chuck Renslow (founder and current president of the International Mr. Leather Contest and The Leather Archives & Museum).
Physique / beefcake magazines were soft gay porn for an earlier, more censorious era. From Wikipedia:
Beefcake magazines were magazines published in North America in the 1930s to 1960s that featured photographs of attractive, muscular young men in athletic poses. While their primary market was gay men, until the 1960s, they were typically presented as being magazines dedicated to encouraging fitness and health: the models were often shown demonstrating exercises.
Because of the puritan culture of the era, and because of censorship laws, gay pornography could not be sold openly. Gay men turned to beefcake magazines, which could be sold in newspaper stands, book stores and pharmacies.
Mars was a small player in the beefcake market. For a major figure, see my 7/17/16 posting “A remarkable website”, with its section on the physique photography of Bob Mizer.
The space-traveling superhero Flash Gordon. More to the point of the Zippy cartoon is the celebrated muscleman Flash Gordon, the first science-fiction superhero of tv and the movies, with a decided predilection for gender-display shirtlessness, though on the (distant) planet Mongo rather than Mars. From a listing in my 11/14/10 posting “Flash Gordon over the years”, three movie highlights:
the 1936 movie serial starring Buster Crabbe as Flash (and its sequels in 1938 and 1940)
Flesh Gordon, a 1974 erotic spoof of the serials films
Flash Gordon, a [knowingly] campy 1980 film starring Sam J. Jones as Flash (with music by Queen)
I am a great fan of the movie serials and the 1980 movie, each enjoyably campy in its own way. And both containing monuments to shirtless masculinity. Notable moments:
(#5) Buster Crabbe in 1936; his arousing performances transferred to tv attended my very early onset of puberty (age 10) and consequently drove an intense but shame-filled fantasy sex life (so I’m not rational on the subject; there is no desire like young desire, especially when recalled in old age)
(#6) Sam J. Jones in 1980, in a shirtless torture scene
On the Flash of the serials, this thoughtful, funny piece from the tor.com site (“Science Fiction. Fantasy. The universe. And related subjects.”), “The Flash Gordon Serials of the 1930s Changed the Face of Sci-Fi” by Hector DeJean on 8/21/19:
Thanks to the growth of streaming services, a vast archive of antique entertainment is now easily accessible to the public, though whether it should be or not is a matter of personal opinion. In the case of the Flash Gordon serials that Universal created from 1936 to 1940, the debate over such material’s worth is a significant matter to science fiction fans. The serials, starring Larry “Buster” Crabbe as Flash (a character who had first appeared in newspaper comic strips a few years prior) made a powerful impression which is evident in much of the sci-fi films and shows that followed. You can see a clear impact on EC comics like Weird Science, on the original Star Trek, and of course the 1980 Flash Gordon film. George Lucas acknowledged the influence of the serials on Star Wars — a film he made when he was unable to acquire the Flash Gordon film rights.
So the pre-WWII serials are significant, but are they actually worth watching? With their stock characters, recycled sets, cobbled-together special effects, and disjointed stories, you could argue that they qualify only as pure camp. It’s easy to laugh at Crabbe’s earnest heroics, and even easier to mock the tin-cans-plus-sparklers rockets and hair-dryer laser guns. … And yet there is no such thing as perfect entertainment, and if films like Guardians of the Galaxy and The Incredibles can offer important life lessons, one of those lessons is that over-the-top silliness and action-packed derring-do can function together in harmony. … When certain expectations are managed, the early Flash Gordon serials are not just enlightening peeks into the formative years of science fiction movies — they’re also enjoyable films on their own, with enough solid adventure and spectacle to make for a fun ride. And, oddly, the longer they run, the better the ride.
Let’s start with the star, Olympic swimmer Larry “Buster” Crabbe. Crabbe will never ascend to the pantheon of Hollywood greats alongside Paul Newman, Ingrid Bergman, Kirk Douglas, and the rest; he’ll never even make it to the level of Michael J. Fox or Jane Seymour. Yet with his Greek-ideal looks and his athletic build, he may have been, visually, one of the greatest action stars who ever lived. Crabbe’s beefcakeiness is such a part of his Hollywood legacy that even his IMDB profile photo shows him shirtless. [Please stop and admire beefcakeiness in bloom.]
… The campiness of the Flash Gordon serials is thick and the effects are laughable, but this is a rocket ship that we boarded a long, long time ago — and it still flies.
The cartoonist’s Easter egg. Finally, my googling on “Musclemen from Mars” turned up a surprise. From the ComixJoint site, about Real Pulp Comics #2 (March 1973), which had strips by Art Spiegelman, Roger Brand, S. Clay Wilson, Charles Dallas — and, yes, Bill Griffith:
Bill Griffith also reprises his appearance in the first issue, but this time not with a Zippy story, but with a hilarious spoof of the comic artist who had taken the underground comics world by storm by 1972: Richard V. Corben. Corben, who had exploded on the scene in Skull, Slow Death, Rowlf, Fantagor and Fever Dreams, was disparaged (or surreptitiously condemned) by many rebellious cartoonists as a slick, shallow and overtly commercial artist who tried to cash in on the underground culture.
Griffith lampoons the style and substance of Corben’s comic art in “Musclemen of Mars,” which features nude, hypermuscular men and women in conflict over matters of little consequence and minor social relevance. Some might presume that Griffith would retract some of his excoriating satire in light of Corben’s subsequent accomplishments, but I tend to believe he would stand his ground even more today than he did in 1973.
… Real Pulp Comics survived for only two issues and the second one only enjoyed one printing of 20,000 copies.
So it’s not just by chance that the Dingburgers in the final panel of #1 are discussing the comic book Musclemen from Mars.