John Wayne Gacy's Clown Painting

Origins
Excerpt from Wikipedia:

John Wayne Gacy, Jr. (March 17, 1942 – May 10, 1994) was an American serial killer and rapist, also known as the Killer Clown, who was convicted of the sexual assault and murder of a minimum of 33 teenage boys and young men in a series of killings committed between 1972 and 1978 in Chicago, Illinois.

Convicted of 33 murders, Gacy was sentenced to death for 12 of these killings on March 13, 1980. He spent 14 years on death row before he was executed by lethal injection at Stateville Correctional Center on May 10, 1994. Gacy became known as the "Killer Clown" due to his charitable services at fundraising events, parades and children's parties where he would dress as "Pogo the Clown", a character he devised himself.

Effects
Prolonged exposure causes a desire to dress as a clown, but also to commit murder.