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Short for Batshit Insane i.e. beyond crazy

see: Batshit Insane or Bat Shit Insane
Person #1 "I just saw some chick take her clothes off and run down the street naked"

Person #2 "She must be BSI"
by BSI Observer June 04, 2009
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2
Black Screen Idiot- somebody who goes onto a video-chat site and doesnt turn there camera on or they block it from seeing them...... why go on to a video chat site if you arent going to let people see you!!!!
Friend: Yo what are you doing
You: im on chatroulette..... HOLY SHIT another black screen!!!!! im so sick of these BSI's

Friend- yeah i know, im so sick of them
by # your mom July 20, 2011
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3
= bullshit investigation, for those who support the FTP movement and believe that every investigation is total bs, because it ruins the person's privacy
Guy: "FUCK YOU, POLICE!"
*policeman is dead silent*
(after investigation and sanctions)
Guy: "Man... that was a BSI, not a CSI!"
by MindsEyeTHPS April 12, 2017
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