In USSR, a boy talking to his grand-father:
Boy: "What is the Perestroika?"
Grand-Father: "You see these two buckets of coal? One is full and the other one is empty."
GF: "Well... (he walks to the buckets and drop the coal from the full bucket into the empty one)... This is the Perestroika."
B: "But, this is the same thing."
GF: "Yes, but did you hear the noise?"