Beware of the truth!!

Once a rich man bought a robot, which slaps everytime someone lies. One day this man asked his son, "Son, whats your position in your class?", son replied" always first daddy". Immediately the robot stepped forward and slapped the boy, dad said" See when I was your age I always came first", again robot came and slapped the dad. Son started laughing loudly seeing this. Mom not knowing whats knowing there, comes and says" Son you shouldn't laugh at your dad like that". Immediately robot slaps her.... :P :P :P