In addition to randomly generating a man page from /bin, consider mining your command line history and randomly selecting anything whose man page you haven't yet read. You'll want to keep a file of man pages that you've read, to help with that.

And since you're stocking up on C, don't forget that C's standard library is documented via man pages, e.g.

  man -k sprintf
  asprintf (3)         - print to allocated string
  sprintf (3)          - formatted output conversion
  vasprintf (3)        - print to allocated string
  vsprintf (3)         - formatted output conversion
  XtAsprintf (3)       - memory management functions