You have to deserve Whistle Points. But how? When you see a contest picture in the Monthly Contest that is another celebrity than the monthly contest-picture, you can report it. What it means is, if the monthly contest-celebrity is Britney Spears this month, users have to submit Britney Spears-transformations. If you see for example a Tom Cruise transformation in the monthly contest of Britney Spears, it doesn't fit in the contest. So report it, and you will receive a whistle point, for the good behaviour. The one who has submitted the wrong transformation picture, will lose one whistle point.
NOTE: Whistle points can go under zero!!