Engineers drink. A lot. At Case, the Chemical Engineering department is famous for weekly keggers on the quad, and Biomedical engineering department (my department) throws these amazing holiday parties with more alcohol than you can ever imagine.
As for the significance of the greek letters, as far as I know, from my sorority's history, the letters were chosen kind of at random with no real significance. My sorority was founded on the campus of Western Reserve University in 1897 -- and before that, the founding members were part of a social group called "the Greeks" and 2 sororities were formed out of it, Sigma Psi (still a local sorority on CWRU's campus) and Phi Delta Upsilon (which later merged with Phi Mu, the national sorority). As far as I know, the letters were chosen at random because they looked cool together and for no other reason.
