You're not supposed to use things like that or negative physical description to identify customers you're writing about... That's day 1 stuff. You can't write "Big fat bob kicked off again" for example.
That said, a colleague of mine (a woman in her 60's) does it constantly and I have to admit some of them crack me up. We have customer logs for certain things, and amongst many, she has written down "skeletor" as the name of a very tall, bald pale man and my personal favourite - "Mummy's Boy" for a guy who is always on the phone to his mum

. We've also had "Rosie and Jim", "The Clampetts" and "Worzel Gummidge"