Noun. The name given to a Johns Hopkins University phenomenon in which anyone you hook up with will have hooked up with at least five of your close acquintances including friends, roommates, lab partners, fraternity or sorority members, TAs, RAs or past sexual partners. There is a very limited pool of sexually active members of the JHU social community, and students are bound to double (or triple) dip on multiple occasions.
Student A: (pointing) I totally hooked up with that hot Engineer last weekend.
Student B: What? He banged my roommate's best friend, my lab partner AND my TA last month!
Student A: Ugh, really? Hopkincest at its best.