David M. Perry is a journalist and historian. He's the senior academic adviser to the history department at the University of Minnesota. Follow him on Twitter . The views expressed here are those of the author. View more opinion articles on CNN.

(CNN) Army and Navy have been playing each other in football since 1890. In 2009, the game between the two rivals began marking the end of the Division I college football regular season, in a spectacle full of patriotic display and, sometimes, pretty good football.

But this year, the game was marred by an incident involving some members of a small group of cadets and midshipmen who stood behind the announcer during the pre-game show Saturday. They subtly flashed a thumb-to-index-finger hand-sign -- the one we usually recognize as "OK" -- but that both the Anti-Defamation League and the Southern Poverty Law Center say can be associated with white supremacy, though both organizations note that the modified "okay" symbol started as a hoax to trick people into thinking innocuous hand symbols were symbols of hate.

It was captured on ESPN video and now both the Army and the Navy have taken the possible implications seriously enough to launch investigations into the use of the sign at the game. Lt. Gen. Darryl Williams, superintendent of West Point, said he had appointed an Investigation Officer to review "the facts, circumstances, and intent of the Cadets in question." Cmdr. Alana Garas, a spokesperson for the Naval Academy, likewise announced the appointment of a "preliminary inquiry officer."

To be clear: We don't yet know whether the gestures were supremacist, a joke, or game or something else, but recent history supplies a good reason for investigating -- particularly as this incident involves college students.

The modified "OK" symbol began on the website 4chan as an attempt to "troll the libs," and soon also was used by racist groups as a plausibly deniable symbol of their hateful ideologies. The ADL says that "particular caution must be used when evaluating this symbol" because unlike a Nazi salute or other more overt displays of white supremacy , the people displaying this symbol may be indicating something benign (like "OK"), or have just intended it as a joke.

Regardless of the motivations of the young men at the Army Navy game, here's a good rule of thumb: If you are using such a gesture because you think it's funny to pretend that you're a white supremacist, you just might be one.

White supremacy is a serious problem in our military , according to a poll of military members themselves, and the bipartisan defense appropriations bill mandates a new report on extremism within the ranks. But the as-yet-undefined gesture at the game reminds me first of the kind of thing we're seeing far too often from the same generational cohort of those midshipmen and cadets, their fellow American college students.

University educations have been shifting from a widely-admired public good to the subject of bitterly partisan arguments . White supremacists are oozing into this maelstrom, trying to conceal themselves in cries of victimization, nice suits, and re-branding terms like the "alt-right." And jokes.

Internet memes, jokes, and anything that simultaneously promotes white supremacy but allows the perpetrator to claim that they were only kidding, have become a vital tool in the white supremacist playbook.

In fact, a literal playbook -- the style guide to The Daily Stormer, a neo-Nazi online publication, which was leaked to The Huffington Post -- reveals just how this works. In the section on "lulz," to keep the site "light," because "genuine, raging vitriol is a turnoff to the overwhelming majority of people." That is, most people aren't comfortable with hate. The "unindoctrinated should not be able to tell if we are joking or not," the editor writes. The section concludes with the author making it clear that he or she is not joking, and does in fact want to "gas k*kes."

White supremacists on campuses need cover, mostly, to thrive. They seek out college students as new recruits by softening their image with jokes, pop culture references and euphemisms for hate. In a recent book chapter , sociologists Adam Burston and France Winddance Twine found, based on "data from a pilot study of members of a conservative student group," that sometimes white supremacists conceal themselves within conservative student groups, which may then -- inadvertently or not -- distribute white supremacist talking points through their networks.

The authors, for example, describe "James," who shared memes about "killing all members of an ethnic group or political group -- including Blacks, Jews, and feminists." When he insulted Candace Owens, a well-known black conservative, most of his peers laughed, regarding him as "edgy" rather than as a dangerous white supremacist. Through people like James and bigoted memes and humor, the authors argue these groups can then serve as a "gateway" to extremism.

In fact, the 62 colleges victimized by swastika graffiti this year, according data collected by the AMCHA Initiative (a non-profit tracking anti-Semitism on college campuses), stretch from coast to coast, north and south, private and public, secular and religious institutions. It's a national crisis. Not everyone who draws a swastika is an armband-wearing Nazi, but as with the "OK" symbol, if you're drawing swastikas, that might be a tell.

Hate isn't new, but the ways in which hate travels through online spaces, dank memes, and viral moments is. That hate infiltrates our daily life, not just for those of us who learn and work on college campuses, but anywhere -- particularly anywhere that young people can be radicalized by peers who have "bought in."

The good news is that the military is taking this gesture seriously and investigating what those who displayed it meant by it. The military, despite its issues within the ranks including white nationalism and sexual assault , continues to be among the most trusted institutions in America, with confidence levels steadily above the 70th percentile over the last decade -- in sharp contrast to, for example, Congress, the Presidency, religious institutions, and the media.

They have their problems -- most recently The Washington Post unearthed decades of lies about the war in Afghanistan -- but have been handling the semiotic battle over symbols and hate better than many too-cautious colleges. Just days before the game, Army announced that it was removing its slogan -- GFBD (God forgives, brothers don't) -- because it had been appropriated by hate groups. They didn't argue that it was a symbol of history and heritage rather than hate, they just ditched the slogan and moved on.

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This should be a model for what happens next in the case of the "OK" symbol -- and more broadly. I don't know whether the individuals who displayed the symbol at the football game were joking. You don't know whether they were joking. But we both know that these young men seized a big stage -- in front of cameras -- to flash a symbol associated with one of the scariest trends in American society.

We must start treating plausibly deniable white supremacy as if it were just white supremacy, before the joke is on us.