Crazy Space Incest. Term commonly used in fanfiction.
Refers to a romantic/sexual relationship between the characters Simon and River Tam on the show Firefly.
Many viewers of the show felt that there was a romantic, if not sexual, subtext between Simon and River thoughout the series, thus the term CSI, crazy space incest, erupted.
Person 1: I read a Firefly fic yesterday and it had some CSI parts in it. Do you want me to send you the link?
Person 2: Yeah, cool. I love CSI fics.
Light It ~ The CSI Shipper's Community on Livejournal