The creep family is much older, originally describing people you can’t trust because they’re always “creeping around.” In early-20th-century America, a creep or creeper could refer to a sneaky thief, a cheating lover or a despicable person more generally. In later years, the annoying or shady creep begat creepo, creepazoid and creepshow. (And just as you can be creeped out by a creepy person, you can be sketched out by a sketchy person.)

We can thank the fine minds at the Massachusetts Institute of Technology for moving random into the realm of the weird. As early as 1971, according to the Oxford English Dictionary, M.I.T.’s student paper, The Tech, was using random as an adjective meaning “peculiar, strange” or as a noun to disparage people outside a community, particularly the community of computer hackers. (The 1991 New Hacker’s Dictionary provides the example “The audience was full of randoms asking bogus questions.”) Eventually it could refer to unfamiliar faces in any social situation, like a party or a bar, with rando as a slangy 21st-century shortening.

Even if these terms describing creepy outsiders aren’t necessarily novel, the question remains: Why do they occur in such profusion on the U.N.C. slang lists? Eble points out that the words are typically used by women, who currently make up nearly 60 percent of U.N.C.’s student population. Compared with past generations, Eble said, “female students are putting themselves into more dangerous situations than they did in my day,” especially when it comes to dating and partying. Terms like creeper, rando and sketchball come in handy as women deal with men who may try to give them unwanted attention.

In interviews I conducted with Eble’s students, one recurring theme that emerged was the impact of technology and social media on the need to patrol social boundaries. “With Facebook and texting,” Natasha Duarte said, “it’s easier to contact someone you’re interested in, even if you only met them once and don’t really know them. To the person receiving them, these texts and Facebook friend requests or wall posts can seem premature and unwarranted, or sketchy.”

Facebook in particular lends itself to “stalkerish” behavior, Christina Clark explained, and indeed the compound verb Facebook stalk (meaning “excessively or surreptitiously peruse another’s Facebook profile”) shows up in the latest slang lists. “People put things on Facebook a lot of the time to show off pictures of themselves and to meet new people, but some of these new people are undesirables,” Clark said. “Unfortunately, it can be hard to filter these people out without feeling unkind, so this information is available to them, and often it is alarming if they seem to be looking through pictures or constantly trying to find out what you’re up to. These people then become stalkers or ‘creepers.’ ”