Have you ever made a fool of yourself by failing to use the most basic piece of office kit properly?
It's considered basic kit now, but back in the day when the company I worked for upgraded its email system from an ancient Vax/VMS to a shiny new GUI-based client thingy (technical term -- I honestly can't remember the name of the software now 'cos it was before I got involved in any form of email admin), we had a play with the new toys it offered. One of these was an out-of-office function, so I called across the room to a couple of my mates telling them to email me, delighting in their reactions when they got an automatic response saying "Piss off, arsehole!"
You can probably see where this is going.
A couple of weeks later I went on holiday for a week. Yes, I did remember to switch the out-of-office on. No, I didn't remember to change the message to something a tad more professional. Fortunately few people in the company used email at that time, and fortunately it was summer so a good number of them were also away on holiday. Very fortunately the one senior manager who was a tech enthusiast and had seen my message also had a great sense of humour, and laughed himself nearly into a coma after calling me in for a supposed carpeting.