Kiefer Sutherland currently stars on Broadway with Jason Patric, Chris Noth, Brian Cox and Jim Gaffigan in a revival of 'That Championship Season'. For Gaffigan, it's the first time the comedian and TV/movie actor has done theater.

So Sutherland warned him of a particular reality Gaffigan had surely never encountered during his stand-up comedy routines.

"A lot of the matinee performances, a lot of older audiences go. Over a six-month period, if the audience is between 80 and 90 years old, it is not uncommon that someone would actually pass away in the course of your play," he explained on 'Late Night' (weeknights, 12:37AM ET on NBC).

On the first night, during a very quiet scene, the actors heard an audience member gasping for air. They halted the play, and someone shouted for a doctor. Gaffigan was shocked and said to Sutherland, "You're not kidding! First one out of the gate [and] you killed someone already."

Thankfully, no. A woman was choking on a piece of candy. "They got the candy out of her esophagus, and she was absolutely fine." But the incident made Gaffigan a true believer.

Watch Kiefer Sutherland's full interview here: