You may want to ponder the thought of taking a camcorder with you to document those "endearing" moments.
If you do, make sure the date and time stamp is on and you get a nice, steady zoom shot of their behavior.
Sounds like you're heading toward a situation where you very well may need as much documentation (read evidence) as you can garner. The previous video suggestions are also very good ideas.
It's said "a picture speaks a thousand words", and that holds true! But, moving pictures speak volumes!!!!
Good Luck!!!

