The Collaborative International Dictionary of English v.0.48:

Wango \Wang"o\, n.
   A boomerang.
   [1913 Webster]

The Jargon File (version 4.4.7, 29 Dec 2003):

wango
 /wang'goh/, n.

    Random bit-level grovelling going on in a system during some unspecified
    operation. Often used in combination with mumble. For example: ?You start
    with the ?.o? file, run it through this postprocessor that does
    mumble-wango ? and it comes out a snazzy object-oriented executable.?


The Free On-line Dictionary of Computing (30 December 2018):

wango

   /wang'goh/ Random bit-level grovelling going on in a system
   during some unspecified operation.  Often used in combination
   with mumble.  For example: "You start with the ".o" file,
   run it through this postprocessor that does mumble-wango - and
   it comes out a snazzy object-oriented executable."

   [Jargon File]