On Sat, 11 Apr 1998, K Yee wrote:

What exactly is a dummy plug?  I'm kinda sketchy on Neon Genesis
Evangelion (although I do LOVE the series ...  Rei-chan.....).  Err,
anyway, is it a cloning machine?  Hmm, help me out.  Arigatou

it's a plug that pretends to contain a person, specifically rei.

-chris