I think I've spoken about a cockatoo surrendered to us a few years ago. The bird had a VERY colorful vocabulary. I finally figured out who he went to and I spoke to her today because she's bringing him in for boarding. I asked her if he was still as rude as he was before and she said he no longer bites everyone, and he's not cage aggressive anymore. However, when he's really mad at her he will say something terrible. She works from home and has an office on the second floor. Both of her birds are in cages downstairs. The cockatoo will call out to her and usually, she ignores him during work hours. Eventually, he gives up and leaves her alone. One day, in particular, he kept saying "Come here" and finally she said no, I'm working..... I can't even type what he said in reply, but he yelled back at her to do something vulgar to herself and then called her a female dog. She said she had to go into the attached bathroom and close the door so he didn't hear her laughing. Her African Grey never says a bad word, and the cockatoo is like a sailor.
I'm constantly telling people not to teach their birds to swear but there are times I wish Chewy could say what I'm thinking so I can blame it on him and not get in trouble for it.