This will come very easily as you play through the first mission, just keep smashing things and scaring bears without too much time in between and your multiplier will fly up and net you 1,000,000 naughty points in no time. This is across a whole episode rather than each section. If you're struggling with this then there are blue clocks around the map which you can run into and will freeze your multiplier for a few seconds. If you find you have killed all the bears and are still short of the points then go around and smash or sabotage every object and complete the optional objective.