case and paste n.
[from `cut and paste'] 1. The
addition of a new feature to an existing system by selecting
the code from an existing feature and pasting it in with minor
changes. Common in telephony circles because most operations in a
telephone switch are selected using
case statements. Leads
to software bloat.
In some circles of EMACS users this is called `programming by Meta-W', because Meta-W is the EMACS command for copying a block of text to a kill buffer in preparation to pasting it in elsewhere. The term is condescending, implying that the programmer is acting mindlessly rather than thinking carefully about what is required to integrate the code for two similar cases.
At DEC (now Compaq), this is sometimes called `clone-and-hack' coding.