Someone sent me an email with the following phrase. I was wondering if this is a known phrase.
I was just calculating your cake penalty.
The only reference I could find to cake penality is in this site, where it's reported a transcription of comments made during a hokey game, and where the following sentence is used to comment a penalty.
I didn't find any phrase containing cake penalty in the Corpus or Contemporary American English or in the British National Corpus.
Googling the phrase and filtering out unrelated occurances brings up enough hits to indicate that the phrase might have some very narrow currency—though I couldn't discern the actual meaning. There are a couple references to penalties involving various numbers of cakes. I also found the phrase mentioned in the context of tennis on one site.
Many of the hits I filtered out were similar to @kiamlaluno's find and refer to patty-cake or fairy-cake penalties in various sports which I took to mean undeserved or silly.
Cake can also be used to describe something as easy—a shortening of the idiom piece of cake.
Let us know if any of this helps and if you get an answer back from the person who wrote it.