If there's a common theme in the stories told by Robin Williams' friends in the wake of his tragic death yesterday, it's of his fundamental sweetness. Actor and comedian Norm MacDonald contributed a remembrance that may be the sweetest Williams story yet, involving a terrified MacDonald about to perform for David Letterman for the first time. Williams had never met MacDonald, and yet he stopped by his dressing room and improvised a bit for the ages. MacDonald recounted the tale on Twitter, and it follows in chronological order below.

It was my first stand-up appearance on Letterman and I had to follow the funniest man in the world. #RIPRobinWilliams — Norm Macdonald (@normmacdonald) August 12, 2014

I was a punk kid from rural Ontario and I was in my dressing room, terrified. #RIPRobinWilliams — Norm Macdonald (@normmacdonald) August 12, 2014

I was on the phone to a friend back home when the funniest man in the world ambled by. #RIPRobinWilliams — Norm Macdonald (@normmacdonald) August 12, 2014

There was no one else on the floor. In shock, I told my friend who just walked by. Only the funniest man in the world. #RIPRobinWilliams — Norm Macdonald (@normmacdonald) August 12, 2014

I guess he heard me say his name, cause in an instant he was at my side. #RIPRobinWilliams — Norm Macdonald (@normmacdonald) August 12, 2014

He was a jewish tailor, taking my measurements. He went down on his knees, asked which way I dressed. #RIPRobinWilliams — Norm Macdonald (@normmacdonald) August 12, 2014

I told my friend on the phone that the funniest man in the world was on his knees before me, measuring my inseam. #RIPRobinWilliams — Norm Macdonald (@normmacdonald) August 12, 2014

My friend didn't believe me so I said, "Could you talk to my friend, sir. #RIPRobinWilliams — Norm Macdonald (@normmacdonald) August 12, 2014

The funniest man in the world took the phone and for ten minutes took my friend's chinese food order. #RIPRobinWilliams — Norm Macdonald (@normmacdonald) August 12, 2014

I laughed and laughed and it was like I was in a dream because no one else was there. No one. #RIPRobinWilliams — Norm Macdonald (@normmacdonald) August 12, 2014

The place was out of Moo Shoo Pork, and there was nothing he could do about it. #RIPRobinWilliams — Norm Macdonald (@normmacdonald) August 12, 2014

He angrily hung up on my friend and I was about to thank him when he said I hadn't even tried the jacket on. #RIPRobinWilliams — Norm Macdonald (@normmacdonald) August 12, 2014

Then the funniest man on earth dressed me, a complete stranger, and i remember he ended with a windsor knot. #RIPRobinWilliams — Norm Macdonald (@normmacdonald) August 12, 2014

He spoke mostly yiddish, but when he finished he was happy with his job and turned me to a mirror to present myself to me.#RIPRobinWilliams — Norm Macdonald (@normmacdonald) August 12, 2014

No one witnessed any of this. No one. #RIPRobinWilliams — Norm Macdonald (@normmacdonald) August 12, 2014

The funniest man alive was in my dressing room a good half-hour and was far funnier than the set I had to do soon.#RIPRobinWilliams — Norm Macdonald (@normmacdonald) August 12, 2014

ll of a sudden it was, had to. #RIPRobinWilliams — Norm Macdonald (@normmacdonald) August 12, 2014