the only one i can think of now is "you can't have your cake and eat it too."
why not! just stupid
yeah i understand the phrase, it means someone wants to have it all... but it doesn't really make sense... whenever i get a piece of cake, i get it with the intention of eating it. i wouldn't bother getting the cake if i didn't think i could eat it. the phrase would make more sense if it was "he wants to have his cake and date a supermodel"... see THAT would make sense.
yeah it's not like anyone gets cake just for the sake of being in posession of cake.
unless you're a cake collector