...habitually finishes your sentences for you?

this question has come up again, and so did this thread:

http://wordsmith.org/board/showflat.pl?Cat=&Board=words&Number=50673

notes:
1) the person who merely interrupts to say what's on his mind (see link) is known as an interrupter - that's obviously not what we're after.

2) the person who allows this to continue to happen is commonly known as a doormat. :)