HMMM! THIS SOUNDS REALLY FISHY! A MYSTERY GROUP BEGS THE JUDGE TO NOT SEND T.I. TO JAIL!

New court documents have just been filed in an attempt to keep T.I. out of the slammer -- and instead move him into a rehab program ... problem is, T.I. has absolutely no idea who made the request.
Neither T.I.'s people nor the prosecution have any idea what the group is ... besides being an organization of some kind that failed geography class.

T.I.'s lawyer, Steve Sadow, tells TMZ that despite the well-intentioned gesture -- he has no plans to appeal the judge's sentence.