How did a patient's shorts end up in the bin after flu vax?

It was the start of influenza vaccination season once again. I was seeing my first patient of the day, face-to-window-to-face, as previously reported in this blog.

And as is so typical of general practice, I once again encountered a surprise in the course of the most mundane of presentations. 

To give some context to the most unusual occurrence on that day, I need to explain an aborted vaccination