Jocasta is very religious and, because people realized basically everything Derrick did in the house was fake, came to the conclusion that his praying with her had been a way to try and get her jury vote. Also, she was obviously offended at the fact that he was using his family as a strategy in the game (e.g. telling people they are taking food out of his daughter's mouth by nominating him). Not sure how that's voting like a retard.
And Donny does seem like a bitter fuck so I'll give you that one.
