get a slap on the wrist

To receive a very mild, often inconsequential punishment or warning. Bill hasn't been late to school that many times, so he just got a slap on the wrist for his tardiness. Most people are outraged that the corporation is only getting a slap on the wrist after violating so many regulations. I expected to get a slap on the wrist or something for making such an inappropriate joke, but then they turned around and fired me!