From Longman Dictionary of Contemporary Englishtake the caketake the cake (also take the biscuit British English) informal to be worse than anything else you can imagine I’ve heard some pretty dumb ideas, but that takes the cake! → cake
Examples from the Corpus
take the cake• You've done some pretty stupid things, but that really takes the cake!• But the collective foolishness of amending the Constitution wholesale really takes the cake. 