Bradley Cooper had a surprise guest starring role in the Season 4 premiere of "The Righteous Gemstones" on Sunday, setting the tone for the final season of HBO's hit comedy.

"I never thought we’d get a guy of his stature to wear a period piece wool costume in 90 degree weather for 10 days straight," McBride says of casting his surprise Civil War set final season opener. "And for no money.

I sent him the script and he called me back pretty quickly,” McBride tells PEOPLE before explaining what happened next