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3.
acronym: Good Sounding Bad Idea. An idea that sounds exciting or plausable, but upon further thought or execution is revealed to be astoundingly dumb and/or dangerous.
1 - Brian suggested all 20 of us go to the party, when only he was actually invited.
2 - Cat decided to ride her bike to school as exercise, disregarding the fact it was 10+ miles away and she needed to be there in 30 minutes.
by skyywise May 26, 2004
 
1.
Good sounding bad idea- a notion that seems great on the surface, but when put into action is actually bad.
At the time, who knew that communism was just another GSBI?
by REBECCCCAAAA October 13, 2005
 
2.
Good Sex, Bad Idea

Self explanitory...leads to disease, pregnancy, and unwanted phone calls
When Bruce awoke and looked at Geoff, he realized he had fallen for GSBI.
by Joe Hasbeen October 13, 2005