slap on the wrist 

1)An unsevere punishment.

2)A warning.

1) Joe: Are you sure I should steal that car?
Fred: Yea, go for it! If you get caught you'll just get a slap on the wrist.
2)Officer: I'll let you two off with just a slap on the wrist this time for speeding.

slap on the wrist by benormous May 4, 2006

Obligatory, judicial, slap on the wrist 

a light slap on the wrist resulting from misconduct

I gave Tim an obligatory, judicial, slap on the wrist when he said an unsavory word.

Obligatory, judicial, slap on the wrist by Nicholas Helpa August 20, 2006