A few weeks into their first tour together in almost three decades, during a performance in Las Vegas, Cheech Marin and Tommy Chong took a break from their comedy skits about counterculture, rebelliousness and drugs so that Mr. Chong could perform a stand-up set about counterculture, rebelliousness and drugs.
Mr. Chong, 70, was delivering his routine when he saw Mr. Marin, 62, grimacing and waving at him from offstage.
In his meandering, hey-dude drawl, Mr. Chong recalled, "I realized I did the same joke twice."
"I was shouting at him," Mr. Marin said. "I was like, 'No, no! Not that one, no!' "