The Pittsburgh Poison Center developed the Mr. Yuk symbol in 1971. The depiction of a green, gagging face with an extended tongue is used by Children’s Hospital to promote prevention education through affiliated hospitals and poison centers. In the testing program, children at day care centers selected Mr. Yuk as the symbol that represented the most unappealing product. Among the other symbols used were a red stop sign and a skull and crossbones. Interestingly, the children found the skull and crossbones the most appealing symbol.