How do I deal with my racist cousin?

My cousin is a racist and it really p!sses me off. He says a bunch of racist things when he's around white people but is too much of a coward to ever say anything to a person of a different race. Whenever I tell him to stop it and call him a scum bag he says,"Thanks." As if its a compliment that hes racist. He makes me so angry and I was considering punching him in the face because I know plenty of people from different races and would love to introduce them to him and see how tough he is. Now hes lifting weights and he thinks he's super tough even though he's just a lanky bean pole, and his comments have gotten worse. How do I get him to stop?