Reb Menachem Mendel, the Rebbe of Kotzk, was known to be an extremely sharp individual. This sharpness was already apparent during his childhood, as seen in the following story:

Once, the cheder rebbe turned to Menachem Mendel and offered him a nickel if he could tell the rebbe where HaShem is. The young Menachem Mendel immediately replied "I'll give you a dime if you can tell me where He isn't!"