His character was given multiple personality disorder, which allowed Kaufman to randomly portray other characters.
In one episode of Taxi, Kaufman's character came down with a condition that made him act like Alex Reiger, the main character played by Judd Hirsch.
Kaufman first used his Foreign Man character in nightclubs in the early 1970s, often to tell jokes incorrectly and do weak imitations of famous people before bursting into his Elvis Presley imitation.
Kaufman, Clifton insisted, was attempting to ruin Clifton's "good name" in order to make money and become famous.
As a requirement for Kaufman's accepting the offer to star on Taxi, he insisted that Clifton be hired for a guest role on the show as if he were a real person, not a character.
Kaufman also had an elderly woman (Eleanor Cody Gould) pretend to have a heart attack and die on stage, at which point he reappeared on stage wearing a Native American headdress and performed a dance over her body, "reviving" her.
The performance is most famous for Kaufman's ending the show by actually taking the entire audience, in 24 buses, out for milk and cookies.
In 1982, Kaufman brought his professional wrestling villain act to Letterman's show with a staged encounter with Jerry "The King" Lawler of the Continental Wrestling Association (although the fact that the altercation was planned in advance was not publicly disclosed for over a decade).
Kaufman died of lung cancer in 1984, at the age of 35.
He would proceed to tell a few (purposely poor) jokes and conclude his act with a series of celebrity impersonations, with the comedy arising from the character's obvious ineptitude at impersonation.
For example, in his fake accent Kaufman would say to the audience, "I would like to imitate Meester Carter, de president of de United States" and then, in exactly the same voice, say "Hello, I am Meester Carter, de president of de United States.
For a brief time, it was unclear to some that Clifton was not a real person.