I remember in orientation for my first internship the HR lady disparaging Chinese Communist party and the phrase "happy ending" may have made an appearance during that part of the presentation. It was absolutely perfect for the demographics of the audience (a bunch of college kids) but man did it ruin every BigCo orientation since. I think she missed he calling as a comedian or some sort of entertainment professional.

I had one orientation where the presenter showed images of the men and women who had jumped out of the WTC during 9/11

Then he cut to slides with several enemy combatants, followed by a massive explosion, followed by a large smoldering crater, and said "Pay back is a real bitch."

The most gruesome briefing I remember from the military was the dermatologist prior to fortnight leave.