Judge Liew Thiam Leng said on Thursday the two culprits had carried out a premeditated crime after previously scouting out the scene.
Although the accused pleaded guilty, he accepted the prosecution's demands for a severe punishment, arguing that it should also serve as a deterrent to others.
The corporal punishment is to be administered with a cane against the prisoners' naked buttocks
"This is the darkest episode in my life," the 22-year-old accused told the court. "I'm so upset with myself that I carried out this idiotic act."
"I promise never to do such a thing again," his 21-year-old partner in crime said. "I must not only apologise to you but also to my family, who I have let down."
Their defender, Christopher Bridges, pleaded for a five month jail sentence and three canings. He also appealed for leniency.
"Since I met the two for the first time I have seen a clear transformation. I believe they deeply regret their crime," he said.
As proof, Bridges cited the fact that the family had gathered money and sent train operator, SMRT a cheque to cover the repair of the damage.
SMRT, however, sent the cheque back.
The accused were brought into the court in handcuffs. Both wore white t-shirts with the inscription "prisoner" on the back.
Left of the judge's lectern stood the evidence: twelve spray cans.
Spraying graffiti is considered a serious crime in Singapore. The city-state places considerable emphasis on discipline, order and above all cleanliness. Vandalism is severely punished.
In 2010 a Swiss man was sentenced to five months in jail and three canings for a similar crime.
The two youths from Leipzig were arrested in Malaysia two weeks after the crime.
Since then they have been detained in custody, a period which will be included in the sentence.
They are due for release in August.