Mr. Yuk: Pittsburgh native Mr. Yuk has officially turned 50 this year.

In 1971, Dr. Richard Moriarty, a pediatrician and clinical professor of pediatrics at the University of Pittsburgh School of Medicine, who also founded the Pittsburgh Poison Center and the National Poison Center Network, designed Mr. Yuk after he decided that the Jolly Roger (skull and crossbones) symbol previously used to signify poison was no longer a deterrent for children.

“Children are relating the danger symbol for poison with pleasant surroundings,” Moriarty told the Pittsburgh Post-Gazette.

It was believed the confusion that ensued may have even led to an increase of poisonings in the area.

Moriarty also noticed that many calls were coming into emergency rooms about poisons, when they should’ve been contacting the poison centers first.

“Frantic parents were making mad dashes to emergency rooms when what they needed to do was to call a poison center, get the right information and, more than likely, sit tight,” Moriarty told the Western Pennsylvania History journal.

Moriarty assembled focus groups of young children to help with the design and color, to determine which configuration was the most unappealing. He experimented with different colors of green, along with “mad,” “dead” and “sick” facial expressions. The children were asked to rank faces according to which they liked the best and the sick face, a sour expression with the tongue sticking out, was least popular. One child called the chosen shade of fluorescent green “yucky,” which is what gave the design its name.

After its creation, Mr. Yuk stickers were used to promote poison centers across the United States. The stickers often contained the toll-free number, 1-800-222-122, for the national poison control center.

Mr. Yuk is a registered trademark of the UPMC Children’s Hospital of Pittsburgh and protected by copyright.