GDI
1)Essentially indicates that there is nothing for which Greek people cannot come up with a particular label.
Fabulous at being apparently unable to handle ambiguity or individuality of any variety, the term GDI is a universal label applied to all college students who choose not to participate in the Greek system.
Whether the apparent obsession with labeling everything belies rampant intellectual laziness, extreme insecurity expressed in a fear of what is "different" from a certain perspective, or both is an open question.
Either way, the same mentality extends beyond the categorization of the college social structure to brand names (are you a Chanel girl? an Abercrombie man? an Alpha-Delta-Zeta or a Kappa-Gamma-Blamma?), and beyond that to even more insidious forms of labeling, such as racism.
However, it all likely comes down to extreme insecurity being expressed in one particular way; label everything, achieve nothing, derive self-esteem instead from trying to look down upon anyone whom you define as an A instead of an B.
2) A derogatory term used by members of Greek organizations to describe someone who has sufficient intelligence and social skills to simply make friends, not pay for them.
"Look at that GDI, he'll go somewhere in life, unlike the legions of coked out worthless douchebags who were misled into thinking that joining a ****ing frat was a smart decision."