The media obsession with President Joe Biden’s age is an ongoing bad joke—especially with Donald Trump right there, spewing utter nonsense. At a speech to union auto workers Thursday, Biden deftly made that point, not through planned remarks but by seizing an unexpected moment and turning it into a good joke.

“They just need to be given a shot,” he was saying. “A fair shot and a fair wage. That’s not too much to ask.”

At this point, a thud interrupted him. Someone must have fallen, because Biden looked over and said, “You okay?”

This is where it gets good: Biden followed that with a pause and a glance around before saying, “I want the press to know that wasn’t me.” As the audience cheered and laughed, he then turned and did a pretty accurate impression of Trump’s impression of him supposedly staggering, bewildered, away from a podium.