It's my user name wherever I need one.
It started out simply because my husband loves my long hair, and said "Why not Rapunzel?", when I was trying to think of a user name several years ago. Then when I started signing up for this and that, and discovering that names of that sort are usually already taken, rather than accept Rapunzel17 or some other number that means exactly nothing to me, I added my birth year -- a large enough number that it's not usually taken, and -- surprise! -- I can remember it!
Now I've said too much, too, but I don't need to worry about killing all of you, because TONIM68 will already have done it for me