Sometimes it won't take a lot to piss off a stranger, prompting them to hurl abuse and profanities at you.
If, however, you manage to do something that makes a bird pissed off at you, it must have been pretty special.
This guy - who looks as if he didn't actually do much wrong - was obviously on the bad side of this crow. So much so, it decided to learn English and say "fuck you" to him.
It could be that the bird is just generally pissed off at the world. Maybe there's not enough food to steal? Who knows.
All we do know is that it's rather funny that what he said sounds an awful lot like 'fuck you', so for that, he's alright in our books.