easy as pie, piece of cake those American phrases do not make sense if you translate them to other language literally but those are good examples of how they are fit into American culture. (No, I don't mean tons of sugar ;p)
Here's a Japanese idium neko no hitai means cat's forehead and it used to describe a tiny Japanese backyard originally and we use it to describe how small something is.
(photo by http://www.flickr.com/photos/mindas)
I wish I could have a backyard like this.