bag on the side

bag on the side n.  An extension to an established hack that
   is supposed to add some functionality to the original.  Usually
   derogatory, implying that the original was being overextended and
   should have been thrown away, and the new product is ugly,
   inelegant, or bloated.  Also v. phrase, `to hang a bag on the side
   [of]'.  "C++?  That's just a bag on the side of C ...."
   "They want me to hang a bag on the side of the accounting
   system."