BSG

Blue Super Giant
Found on http://www.translationdirectory.com/glossaries/glossary142.htm

BSG

Acronym used to refer to ESPN.com writer Bill Simmons, who before ESPN was known as the Boston Sports Guy.
Found on http://www.footballoutsiders.com/info/glossary_general

BSG

British Society of Gastroenterology
Found on http://munksroll.rcplondon.ac.uk/Home/Glossary
No exact match found