This California case [link is to a PDF file] could make anyone squeamish so don't proceed if you are faint-of-heat. You have been warned.
It seems a woman was riding, on a lake, as a rear-seat passenger on a two-person water-jet powered craft when, while in motion, she fell off the back of said craft.
For one brief instant, the fast moving jet of water exiting the back of the craft was aimed directly at her buttocks. In that frozen in time moment, the water tore through her bathing suit, into her anus and then into her internal organs, causing extensive and permanent injury.
According to the case, she no longer has control over her bowls or bladder. In addition, she has lost feeling from her waist down to her knee, essentially ending her sex life.
Leaving aside who was at fault, and realizing that this type of injury, according to the case, appears to be rare, the thing to remember is that these can be dangerous vehicles and you should pause and reflect on what that means and what you can do to avoid similar injury.