I love the phrase mero mero, meaning top banana (e.g. "No pierdas el tiempo, pide cita de una vez con el mero mero"). I have a vague idea I know some more phrases like this, with the same word appearing twice, changing either the meaning or adding to it, but after a couple of days of letting this roll around in my mind, nothing is coming.
In addition to listing the phrase and explaining what it means, either in Spanish or English, please also include an example sentence and the country or region where you've heard it used, or the author and title if you learned it from a book.
