Really now, I've been caught doing worse things on the job. K-Mart, January 2002, thirty minutes before closing, pet food aisle. Me, Mrs. Dilworth and a 2 foot lava lamp straight out of the display case. Use your imagination.
It's not your typical work-related injury, but these things do happen... especially when someone is intentionally thrusting their foot into your vagina. It could've been worse - a flesh wound via jagged toenail... that would've put her out of work for good.