I dont find it offense either, b/c as many said its a term that derived from those who were Greek. And the term is not limited to Greek jargon either. Before I was Greek and gave my own definaition of the word, I called myself a GDI at times. Here's how I see it. You have....

Greeks: People who are members of Greek lettered organizations (generally social/service)

Non-Greeks: Those who are not members of Greek lettered organizations and who may not agree with Greek Life, but are opened minded and do not bash it, will listen to the positives of it, and then move on with their day.

GDI's: ANTI-GREEKS. Only negative comments about Greek Life come out of these peoples mouthg and they base their opinions on some true but mostly false facts and fictional TV movies. They often use the argument, "I don't have to buy or pay for my friends". Instead of trying to see the good that Greeks do all they see is Negative. These are people who will dump their sig. other or friends because they went Greek. People who like to be close-minded and plain old Ignorant.

And if they want to be this ignorant, then I am in no way offended that someone would call them a GDI. After all they label themselves that.

My 0.02 cents