"Data potato du wop du wop" was an error message from firmware in Dartmouth College's Avatar terminal. The message indicated an internal error and was not supposed to be seen by terminal users. Apparently this was not always the case.
The words are taken from a New Yorker cartoon "What About Us?" by Stevenson, captioned in part
Threatened cutbacks in energy totally ignore those of us most directly affected, says an electric toothbrush in Riverdale New York.
A computer in Cambridge, Massachusetts has already begun its protest, endlessly repeating "Data potato ... du wop ... du wop ..."
The Avatar was used at Dartmouth in the 1980s. It was a Zenith Z-19/Heathkit H-19 terminal, modified by adding a Z-80 processor and RAM. Jim Perry wrote the firmware. This allowed it to support interactive screen editing without burdening the DCTS Honeywell mainframes with character processing. Avatar firmware was also ported to the DEC GiGi. Several Unix systems also supported its redactor host screen editor. When they became available, Apple Macintoshes replaced Avatar terminals.
In the mid-90s I used redactor on Ultrix from my home SE/30, and found it to be effective, a lot like editing over sftp.
Some references to this error message spell it "Data potato doo wop doo wop".