Justin Bieber -- Grade A in Egging Probation

Life is sunny side up for Justin Bieber -- whose latest meeting with his probation officer went off without a hitch ... TMZ has learned.

Biebs put on his best baggy b-ball shorts and a ball cap for his probation check-in at the Santa Monica Courthouse Thursday. The meetings are required after his plea in last year's egging vandalism case.

According to law enforcement sources ... Justin got glowing reviews and seems to be sticking to his word of keeping his nose clean. As we've reported ... our sources say he's serious about turning over a new leaf.

Probation officers don't judge fashion ... lucky for Justin.