In Hungarian, if you want to express that something is mind-blowing, you say megáll az ész "the mind stops". (For example, the National Geographic Channel's show Brain Games is titled Megáll az ész! in Hungarian.)
In our family, if we want to go even further than that -- to really express our utter incredulity (usually at the stupidity of something) -- we add a bit of a paraprosdokian/play on words: megáll az ész... és legelni kezd, which is something like "the mind stops... and begins to graze". As in, our mind stopped not in the expected sense of reconsidering our assumptions, nor even in the "normal" metaphorical sense of hitting the stop button on the music player, but in the (rather ludicrous) sense of a four-legged animal pausing in its amblings to nibble at a likely-looking tuft of grass.
Is there a similar two-part idiom in English for being utterly flabbergasted at something? By two-part, I mean is there a basic idiom for surprise that can be intensified by extending the idiom/metaphor? (Sort of like there's "pretty please", and then there's "pretty please with a cherry on top".)
(The root cause of this question, if you will, was a post on a blog listing newly-popular baby names that end in -er, where one of the names listed was Lucifer. I wanted to express my reaction to this, and "the mind boggles" just didn't seem to come even close.)