Buck McCoy was a very famous Western movie star and recovering alcoholic. He is 76 years old. 
Bart first met him after being saved by Buck from a ferocious dog. During his heyday, Buck learned a lot of tricks involving animals and, when sober, boasted impressive marksmanship. After realizing how much it saddened Bart knowing Buck was an alcoholic, he quit drinking, only to start again after Bart was content. Buck then even managed to save Springfield from criminals. He's not only addicted to alcohol but drugs and pornography. Homer then took the magazine out of the trash and said "There's nothing wrong with a little hey-hey".
Behind the Laughter
Voiced by Dennis Weaver, Buck McCoy's only appearance is in "The Lastest Gun in the West". He also looks a lot like the 40th President of the United States Ronald Reagan, who before being president was an actor in many westerns. The name "Buck McCoy" is likely to be a reference to western star DeForest Kelley's roles. Kelley appeared on The Lone Ranger as Sheriff Buck McCall and on the science-fiction television series Star Trek as Dr. Leonard "Bones" McCoy. He may also be based on Hollywood Legend John Wayne as he too was a well known Western Film star.