"Dipe" in "Dipe-ducat" (subway ticket) in 1922 "Flappers' Dictionary

[Cohen, Gerald Leonard]

In a Sept. 27, 2003 ads-l message, Barry Popik presented a Flappers' Dictionary (14 Sept. 1922 _Edwardsville Intelligencer_ (Edwardsville, Illinois).
Several items call for attention, but none so much as "Dipe" in "Dipe-ducat -- a subway ticket." I checked the microfilm. The spelling really is "Dipe."

   But what does this word mean?

Gerald Cohen