The longer form of the story is kind of amusing. It was actually a "pick-up" group. A brass quartet that was needed for a single afternoon of short lecture/recitals at a museum. We had 3 doctoral candidates booked (1st trumpet, horn, and trombone) and this poor freshman music major got thrown into the crucible with us on 2nd trumpet. We had selected pieces that allowed for a very simplified music history lesson in the talks between pieces, and repeated the show about 4 or 5 times that afternoon. At each show I would introduce all the members of the group. At the last performance I introduced the 2nd trumpet player last, and then added ". . . and since he's such an accomplished music history student, we're going to let him tell you about the next piece." At which point I sat down (We had told him to be ready to talk, but I'm not sure he believed us.). If he had failed to get up, or not been up to the task, I would have rescued him, but it wasn't necessary. He had been paying attention all afternoon, and after rehearsing with us he was ready for anything. He got up and told them about Handel, and we finished the concert. I would never do that to anyone on the first show, but after hearing me talk about the piece 4 times he had plenty of material, and he managed to remain calm and simply take the situation as it came.