obfu is certainly the shortened obfuscate:

1536, from L. obfuscatus, pp. of obfuscare "to darken," from ob "over" + fuscare "to make dark," from fuscus "dark."

UPDATE: After some digging, I may have found the first ever internet related use of the term obfu; used in a post by
John W. Cobb on Feb 20 1992, at 11:18 am.
John's signature includes the line, -Olympic Medalist in Obfu-skating (in sci.physics.)
John may now reside at Oak Ridge National Laboratory. Perhaps an ORNL Monk can find him for comment?

Later references are made in alt.sources - Nov 12 1993, 11:01 pm by Ury Segal.