Couple of years ago I was flying NYC-LHR in business and due to bad traffic in Manhattan ended up cutting it very close to departure. I remember running through the terminal praying to be on time.

Once at the gate, GA scanned my boarding pass and then sadly uttered:"We are sorry, sir, but the flight is overbooked and there is no seat for you". Before I could say anything she added:"But I don't think you will mind... we do have an upgrade for you in the First Class"

The experience itself was underwhelming. It was one of old AA planes with all the random signs in Japanese. It must have been 30 years old, rattled like a tin can, and the food was barely acceptable

That said my 2nd upgrade to First Class was more memorable. It was a short ORD-LGA hop on Delta, but it happened on a day of severe t-storms and my flight was the last one not cancelled that day.