Here's a sad insight into child abuse: "the vast majority of child abusers are parents, relatives, or trusted adults, not strangers," according to the RCMP.
That's what makes this ad from Anar Foundation, a Spanish organization that fights child abuse, so clever: it hides its true message - as well as the number of kids-only helpline - from any adult who might be the perpetrator of abuse.
The poster was created using lenticular printing technology, which means that adults and kids (or anyone under 4' 5") see it differently.
Adults see an image of an unbruised boy, with the message "sometimes child abuse is only visible to the child suffering it."
But for kids, the poster looks different.
They see a boy whose face is cut and bruised - and the message for them is "if somebody hurts you, phone us and we'll help you." There's a phone number included on the poster.
It's a neat trick on the part of the ad agency that created it.
But it also points to the reality that the RCMP highlighted: many kids who are victims of abuse live and travel with their abuser, and the ad is designed to give kids the courage to call the number by preventing their aggressor from reading it.
"It is a message exclusively for them, hidden from adults' eyes," said Grey Spain, the agency behind the poster.