OK. First things first, it is my regretful duty to inform you that you have stumbled across some extremely fake history. Totally and flamboyantly bullshit. Also, no skin off my nose, but for the benefit of anyone on work internet, it's also very NSFW.

So, the claim that compulsory fellatio was a requirement of promotion within the ranks of the Roman army prior to the Marian reforms is pants-on-head nonsense. Throughout recorded Roman history, both Republican and Imperial, both pre-Christian and Christian, it was never mainstream socially acceptable for a respectable citizen male to fellate anyone. He could, more or less socially acceptably, be fellated by a man who wasn't a respectable citizen (i.e., by a social inferior such as a slave), but to be the receptive partner in such an act invited disgrace. The same went for receptive roles in sex more generally. Prevailing social mores dictated that while Roman citizen men might penetrate others, they were not themselves to be penetrated.

Just for a sample of how the Romans actually felt about forcing military men into receiving sex around the time of the Marian reforms (named after the Roman general Gaius Marius), an element of Gaius Marius's biography as recorded by Plutarch is that when Marius was commanding the army, one of Marius's relatives, an officer named Gaius Lusius, tried to force himself on a younger soldier named Trebonius. Trebonius might have been a junior soldier, but he wasn't going to put up with that: he killed Lusius on the spot. Trebonius was put on trial before Marius for murdering Lusius, but when Marius heard that the reason for the murder was fending off Lusius's sexual advances, he not only acquitted Trebonius of murdering his superior officer (and Marius's relative) but also awarded him laurels for valor.

This unbiased handling of a case involving his relative was widely admired and later helped Marius win an election for the consulship, the highest office in the Roman Republic.

So yeah, far from the article's claims that sex was officially forced on any Roman soldier who wanted to be promoted, Plutarch's account of the same time period tells us that the Romans were actually giving out awards for killing senior soldiers who tried to coerce subordinates into it.

I hardly want to bother with the ridiculous claims about how the Romans measured the sunlight passing over the Colosseum and executed the soldier if he wasn't done in time. Suffice to say that the Colosseum did not even exist yet. Not just bullshit, sloppy bullshit from someone who doesn't know even the basic timeline of Roman history. The Colosseum was built nearly two hundred years after the Marian reforms.

I'll end by saying that every single detail given about what allegedly happened at the actually-not-built-yet Colosseum is just as fake.

This being r/AskHistorians, though, it's not enough to say that something is bad without providing better! Happily, the Roman army is a frequent subject of questions here, as is homosexuality in the classical world, so below are links to some past questions and answers on various topics covered... can I say covered when it's such bull? Let's say topics raised in that article.

Re male-male sex in the classical world, check out previous questions and answers:

• What was it like being gay in ancient Rome? How socially acceptable did the Romans view it? Answers by u/thebatteryhuman and u/MarsTheGodofWar. An older thread, but it comes with translations of ancient Roman sex insult poetry!)
• Did ancient Rome's perception of homosexuality change after Christianity became the dominant faith? A newer thread with answers by u/jdwright1989.
• How common was homosexuality (or what we'd now see as homosexuality) in ancient Greece? with a long series of excellent answers by the inimitable u/cleopatra_philopator. Although this thread covers Greece, not Rome, these societies increasingly came into contact with and influenced one another over the course of classical antiquity.

Re the Marian reforms, the reason you couldn't find any info on them is probably either a) they are misspelled in the article or b) they are said to have involved wealth requirements to serve in the army, not penis size requirements. You would not have found any information on the latter since that was never a real thing.

Here are some previous questions and answers discussing the Marian reforms:

• The Marian Reforms - looking for a good explanation. This elderly answer by the mysterious [deleted] gives an old-fashioned, conventional take on what the Marian reforms were; namely, Marius greatly increased Roman manpower by allowing men without property to join - but since men without property had less of a stake in defending Republican principles and more of a stake in supporting their general in exchange for rewards, in the long term this led to decreased loyalty to the Republic, more loyalty to the specific general, and the rise of warlordism and civil war.
• Why exactly did the Marian reforms of the Roman military cause the loyalties of the soldiers to shift to their generals? This more recent question, answered by u/XenophontheAthenian, draws on more recent scholarship to question whether the Marian reforms really happened as described or whether they were never anything but a convenient historians' myth.