McCarthy, who trained initially as a painter, works primarily in video and sculpture. His earlier art was influenced by Viennese Actionism, which strives to transcend the limitations of painting by using the body as paintbrush or canvas, and he eventually incorporated bodily fluids in his works.

His 1974 work Painting, Wall Whip featured a video of his headed painted red and his body covered in ketchup, mayonnaise, raw meat and in one instance, feces.

Class Fool, created in 1976, watched as he threw himself around a classroom covered in ketchup until he was too injured and dazed to continue, subsequently vomiting and then inserting a Barbie doll into his rectum.