Contraction of Miss Dipsy, i.e. Miss Dipsh--. Contraction is meant to be a polite cut.
I made it up in college to apply to naive or very immature college girls age 25 and under. Usually sits at a desk answering phones and saying things like-"Gee, I'm not sure. Can you call back, like, never?"
I went to college at a late age and I was apalled at the immaturity.