Origins of grewster are from the Tri-College Consortium, which is between Swarthmore, Haverford, and Bryn Mawr.
Grewster is an affectionate nickname for such a person.
Grewsters usually hang out in packs with other grewsters, but can often be found with the most elite intelligent population.
Xander, my friend, you know, the Grewster...
Hey, Grewster, want to go grab a bagel and lox with me for breakfast tomorrow?