First, I was invited to speak at a science communication meeting in X in November. Next, I was invited to host an event at Y around the same date. Then I was invited to speak at Z on the same date. Since I’d already been to a few science communication meetings similar to the one in X, I figured Y was more important, so I declined to come. But when the Z invitation arrived, I found it was more important since it was a national event, so I declined Y. Finally, the Z event’s organisers put me on a manel; when I refused to participate, they rescinded their invitation. Now I was available again but I couldn’t go to X or Y because when I turned them down, I had nominated others in my stead and they had confirmed their participation.