Mine is just a combination of a shortened nickname from just out of high school (Donkey) and my D.O.B.
Not secure, don't care...
I got sick of writing out my original when logging in as it was too long.
Donkey_Snickers
That was back when the tagline for the Snickers chocolate bar advertisements was "Really satisfies"...
I had a bit of an ego regarding my sexual prowess 20 something years ago...