Nelson was charged with misdemeanor marijuana possession back in November ... after U.S. Border Patrol in Texas found weed on his tour bus -- but the prosecutor in the case is willing to let Willie off with a $100 fine ... if he sings "Blue Eyes Crying in the Rain” INSIDE the courtroom.
According to the prosecutor, the song would count as his community service -- but Willie's punishment ultimately rests in the judge's hands.
No word if Nelson will accept the offer ... but it's a good deal -- because if he gets convicted he faces a maximum of 180 days in jail and a $2,000 fine.
