Virginity Flag

Where a person's virginity or absence thereof can be confirmed by some sort of sign or symbol immediately visible on them (that is to say, definitely not requiring a gynecological examination). This can work through magic, Applied Phlebotinum, or simply social convention.

Compare Did You Just Have Sex?, Sex Dressed, Virginity Makes You Stupid, Virgin Power, Virgin Vision (the unjustified form of this).

Anime and Manga

 * Everyone in the world of Loveless has kitty ears and a tail that fall off when they lose their virginity. This connection is conveyed through social cues within the story, and exactly what point defines 'the outer border of virginity' is never really defined.
 * Partly because, for all the sexually charged atmosphere, the lead is a twelve-year-old boy, and this is technically a mainstream manga, and is not going to turn into porn. I guess someone could provide him with a sex-ed lesson at some point, but it's not really that kind of setting. A grown woman with ears is teased about still having hers, and having already lost their ears is a sign of some enemy characters' pitiful depravity, but the wider social implications, for example in high school or religious orders, aren't really explored.

Film

 * The song in Pod People has an audio technician wearing a shirt that reads "I'm a Virgin".
 * Parodied in the MST3K bit from the same episode, where TV's Frank wears a similar shirt.

Literature

 * In the SF shared world of Medea, the resident alien females lose a pair of legs after having sex.
 * In Madeleine L Engle's Many Waters, only "innocents" can ride unicorns. (Otherwise, they disappear.)
 * In Nineteen Eighty-Four, a scarlet sash is the emblem of the Junior Anti-Sex League, which advocates celibacy.
 * The Yeerks from Animorphs are similar to the Decapodians below: they die after mating. Actually, it's not so much "die" as "three Yeerks merge into one big blob and the blob breaks up into little baby Yeerks". Bizarre Alien Biology, indeed.
 * In Mercedes Lackey's Tales of the Five Hundred Kingdoms, unicorns act as living 'virgin detectors.' Beautiful, beautiful, brainless virgin detectors...
 * All the extra skill and muscle mass that Laura Herrante in Stationery Voyagers: Final Hope had acquired from her multiple respawns immediately disappears within minutes of her first time having sex. To train for the perils of her job, she's forced to Restart At Level One. Only this time, she's not immortal anymore.
 * In The Bible, after Amnon rapes her, Tamar tears her garment that was reserved for the king's virgin daughters. Her full brother Absolom immediately realizes what happened when he sees her.
 * The thranx of the Humanx Commonwealth look a lot like giant praying mantids. Unlike praying mantids, male thranx only lose their vestigial wings the first time they have sex.

Music Video

 * The fan-made video for TISM's "Everyone Else Has Had More Sex Than Me" with everyone's number of either sexual partners or number of sexual escapades written on their shirts. And yep, there's one poor fellow with a "0" on there. And one with "3.5".

Newspaper Comics

 * The one time Dilbert got lucky, his tie was drawn straight.

Theatre

 * In Me and My Dick, the virginal Sally's Miss Cooter wears a flower prominently.

Webcomics

 * This strip of Perry Bible Fellowship.

Western Animation

 * In the case of the Decapodian species from Futurama... simply being alive. Decapodians die soon after mating.
 * So do real octopuses; males shortly after mating, females shortly after giving birth. Few octopuses live to mate more than once.