Why do people say this?  Have your cake and eat it too.  They say it to mean something that is not possible.  Don’t you have to have cake before you can eat it?  It seems to me that if you wan to eat cake, first you have to have it.  Maybe we should say “Save your cake and eat it too”.  That would make more sense.  Maybe it’s the consumption part that is confusing the issue.  Let’s try it with money.  Save your money and spend it too.  See, now that is not possible.  Have your money and spend it too.  How can you spend money if you don’t have it first?  Oh, wait…that’s not a good argument because that seems to be the only money congress knows how to spend!