Worst experience with a coworker thread

i think there have been threads like this but what is your worst experience with a coworker thread?

this is mine:  i work at a day camp and i got paired with a new counselor and she's 24 or 25 and treats me like i'm her CIT though we have the same job but she get paid 10 compared to my 8.50 because she's over 18. She always has these bs ideas for our group and never listens when i tell her they're fucked up.
     so today she decides to do finger painting with 13 seven year olds even when i told her it was bad and so in the end there was paint all over everyone, the chairs, the table, she got mad at me for not being more attentive while she talked on her phone and apparently she was taking the last hour off as personal time so I had to clean up everything, everyone, etc. It sucked.