That's sort of how mine get named. At first I call them something just so I know which is which.
They just... end up getting called something out of left field (for me) and it sticks. Like my Avatar was Blue for the longest time (yeah real original - and she wasn't even the only blue) then I suddenly started calling her Olive. Not for any reason I know of. And others have gotten named by neighbors just like you say. The worst was the polish rooster that one neighbor insisted was Rod Stewart. Glad he's gone. (the chicken not the neighbor - lol!)
The funniest, for me, was Dixie. I have a hatchery one that was attacked as a chick and hurt badly on one hip. She pulled through, but now at 3 years old, walks funny. One day she became Dixie for no reason that I could think of. Then a few weeks later it hit me. You know, I'm over 50 and when I was a child people sometimes did have one leg longer than the other and medicine couldn't do much about it. So those poor folks just had a shoe with a really thick sole and walked a bit oddly. Like my mothers friend, Dixie. Oh my. I hadn't even seen that woman since I was around 6 and this chicken has the same gait. I whispered an apology to the woman who is long gone but the chicken is still Dixie.