We had a Kakariki that we were told would learn to talk. One of our friends spent hours and hours over a couple of years sitting next to his cage saying "Arsenal" over and over again to no avail (he wanted to annoy Mr F who's a Man United fan). The words that I said to him most (on an almost daily basis) were "Go on, bite me again you f*cking bitey little bastard! I f*cking dare you!". All he ever used to say was "Pretty* Rico", "Who's a pretty boy Rico?", "Ooooooh Picorico" and to cackle loudly just like a magpie which I assume he picked up from magpies sat on the chimney. As far as I know nobody taught him the Pretty Rico stuff and we were the ones that named him Rico, prior to that he lived in a cage at a garden centre on his own because he attacked the cockatiels and budgies when they put him in the aviary.
*there could be up to six "pretty"s when he said it
He was a psycho bird, he actively enjoyed attacking people and his "tell" if he was in a bitey mood was something I called big-eye-little-eye. When I'd go to open the cage door if the pupils in his eyes were dilating and shrinking over and over again I knew I was going to be attacked by dive-bombing. If they were normal he'd just come out of the cage and have a fly around, land on my head and sit there for a bit all lovely and cute.